Chart · Temperature measurement

Pt100 resistance chart and curve: −200 to 850 °C (with Pt1000)

Name: Pt100 and Pt1000 resistance chart in °F per IEC 60751
Creator: shukchok
License: https://shukchok.com/en-sa/policies/terms-of-service

Target values for Pt100 and Pt1000, recalculated from the standard, with tolerances in degrees and in ohms. Plus the formula, a °F chart, how to test a sensor with a multimeter, what the cable costs you and how reliable charts on the web are.

By Alexander Scharff, Responsible for contentUpdated 14 November 202618 min read17 sources · 2 datasets

Contents

In short Answer in one sentence

A Pt100 reads exactly 100.00 Ω at 0 °C (32 °F), 107.79 Ω at 20 °C (68 °F) and 138.51 Ω at 100 °C (212 °F). A Pt1000 reads ten times that (1,000.0 Ω, 1,077.9 Ω, 1,385.1 Ω) ².

Resistance rises by about 0.39 Ω per °C (Pt1000: 3.9 Ω/°C), but not quite linearly. Values follow IEC 60751 and the Callendar–Van Dusen equation with α = 0.00385 ^{1, 2}.
IEC 60751 tolerance: class A ±(0.15 + 0.002·|t|) °C, class B ±(0.3 + 0.005·|t|) °C. At 100 °C that is ±0.35 °C or ±0.80 °C ¹.
Of 19 charts we checked online, 6 had an error. Quick check: if 850 °C does not read 390.48 Ω, the chart uses outdated 1983 values ¹³.
2-wire hookup: just 1 m (3 ft) of 0.22 mm² (≈ AWG 24) cable adds 0.4 °C of error to a Pt100. A Pt1000 is ten times less sensitive ².

Key terms in 30 seconds

Pt100 / Pt1000: A platinum temperature sensor. At 0 °C it reads exactly 100 Ω (Pt1000: 1,000 Ω); warmer means more ohms.
Curve (characteristic): The curve that gives the resistance for each temperature. The chart is the same curve in numbers.
IEC 60751: The standard that defines the curve and accuracy classes for platinum sensors. Used worldwide.
Callendar–Van Dusen equation: The formula from the standard used to calculate every chart.
Tolerance class (AA, A, B, C): How far a sensor may be off. AA is the most accurate, C the coarsest.
α = 0.00385: A figure for the slope between 0 and 100 °C. It says nothing about accuracy.
2-, 3- and 4-wire: How many wires run to the sensor. With two wires the cable adds to the reading; three or four wires cancel it out.

How to read the image

Top: a finished probe, a stainless steel sheath with cable. The actual sensing element sits hidden in the tip.
Bottom right: two loose sensing elements of two designs, as fitted inside such sheaths: a flat chip at the top, a small tube below. Both are only a few millimetres long.

Stainless steel Pt100 sheath probe with black cable, next to two loose platinum sensing elements — **Fig. 1** Source: “Pt100 Sensors.png”, Wikimedia CommonsPhoto: dirkhb, public domain, via Wikimedia Commons

How to read the image

From left to right: cable, hex with screw-in thread (identify it with our thread chart), sheath. The sheath is cut open lengthwise.
Inside, two thin wires run through a white ceramic filling to the tip. That is where the sensing element (orange) sits – the actual Pt100.
So the temperature is measured at the tip only. The rest is mounting and leads.

Cut-away stainless steel screw-in RTD probe: cable, hex with thread, sheath with ceramic filling, inner wires and an orange sensing element at the tip — **Fig. 2** AI illustrationSource: shukchok, schematic, not to scale

Pt100 resistance chart (−200 to 850 °C)

All values are our own calculation per IEC 60751 and can be checked with the formula further down ^{1, 2}. The class A/B columns show how far a sensor may deviate from the target value – in degrees and, for checking with a meter, directly in ohms. The full chart in 1 °C steps is in the dataset below.

°C	°F	Pt100 in Ω	Pt1000 in Ω	Slope in Ω/°C	Class A ± °C	Class A ± Ω	Class B ± °C	Class B ± Ω
−200	−328	18.52	185.2	0.432	(0.55)¹	(0.24)¹	(1.30)¹	(0.56)¹
−100	−148	60.26	602.6	0.405	0.35	0.14	0.80	0.32
−50	−58	80.31	803.1	0.397	0.25	0.10	0.55	0.22
0	32	100.00	1,000.0	0.391	0.15	0.06	0.30	0.12
20	68	107.79	1,077.9	0.389	0.19	0.07	0.40	0.16
25	77	109.73	1,097.3	0.388	0.20	0.08	0.43	0.16
50	122	119.40	1,194.0	0.385	0.25	0.10	0.55	0.21
100	212	138.51	1,385.1	0.379	0.35	0.13	0.80	0.30
150	302	157.33	1,573.3	0.374	0.45	0.17	1.05	0.39
200	392	175.86	1,758.6	0.368	0.55	0.20	1.30	0.48
300	572	212.05	2,120.5	0.356	0.75	0.27	1.80	0.64
400	752	247.09	2,470.9	0.345	0.95	0.33	2.30	0.79
500	932	280.98	2,809.8	0.333	(1.15)¹	(0.38)¹	2.80	0.93
600	1,112	313.71	3,137.1	0.322	(1.35)¹	(0.43)¹	3.30	1.06
850	1,562	390.48	3,904.8	0.293	–	–	(4.55)¹	(1.33)¹

¹ Outside the valid range of the class for wire-wound thermometers; no class guarantee there. Film elements have narrower ranges (see tolerance classes). Ohm values for Pt100; multiply by 10 for Pt1000. Rounded half up: 138.5055 Ω becomes 138.51 Ω; class B at 25 °C is exactly 0.425 °C and becomes 0.43 °C ².

Pt100 chart in °F

The same curve at round Fahrenheit values. A tolerance in °C converts to °F by multiplying by 1.8 ².

°F	°C	Pt100 in Ω	Pt1000 in Ω
−300	−184.4	25.20	252.0
−200	−128.9	48.46	484.6
−100	−73.3	71.00	710.0
0	−17.8	93.03	930.3
32	0.0	100.00	1,000.0
50	10.0	103.90	1,039.0
68	20.0	107.79	1,077.9
77	25.0	109.73	1,097.3
100	37.8	114.68	1,146.8
150	65.6	125.37	1,253.7
200	93.3	135.97	1,359.7
212	100.0	138.51	1,385.1
300	148.9	156.91	1,569.1
400	204.4	177.49	1,774.9
500	260.0	197.71	1,977.1
600	315.6	217.58	2,175.8
800	426.7	256.24	2,562.4
1,000	537.8	293.48	2,934.8
1,200	648.9	329.29	3,292.9
1,500	815.6	380.33	3,803.3

Own calculation per IEC 60751, t °C = (t °F − 32) × 5/9 ^{1, 2}. The full chart from −320 to 1,560 °F in 1 °F steps is in the °F dataset below.

Pt1000 resistance table

A Pt1000 follows the same curve as a Pt100, only with 1,000 Ω at 0 °C. Every resistance value is ten times as large, and so are the slope and the tolerance in ohms. In degrees the tolerance stays the same ^{1, 2}.

°C	Pt1000 in Ω	Slope in Ω/°C	Class A ± Ω	Class B ± Ω
−200	185.2	4.32	(2.38)¹	(5.62)¹
−100	602.6	4.05	1.42	3.24
−50	803.1	3.97	0.99	2.18
0	1,000.0	3.91	0.59	1.17
20	1,077.9	3.89	0.74	1.55
25	1,097.3	3.88	0.78	1.65
50	1,194.0	3.85	0.96	2.12
100	1,385.1	3.79	1.33	3.03
150	1,573.3	3.74	1.68	3.92
200	1,758.6	3.68	2.02	4.78
300	2,120.5	3.56	2.67	6.41
400	2,470.9	3.45	3.27	7.93
500	2,809.8	3.33	(3.83)¹	9.33
600	3,137.1	3.22	(4.34)¹	10.61
850	3,904.8	2.93	–	(13.32)¹

¹ Outside the valid range of the class for wire-wound thermometers. Own calculation per IEC 60751 ^{1, 2}.

Dataset: Pt100 and Pt1000 resistance table per IEC 60751, −200 to 850 °C1,051 rows, −200 to 850 °C · Own calculation with A = 3.9083e-3, B = −5.775e-7, C = −4.183e-12, as of 2 November 2026© shukchok, all rights reserved

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Pt100 curve: why it is not quite straight

A Pt100 is often calculated with a straight line: R = 100 Ω × (1 + 0.00385 × t). It is exact at 0 °C and 100 °C, but not in between or above. The standard adds a squared term, and below 0 °C another one ^{1, 2}.

How to read the chart

Left to right: temperature from −200 to 850 °C. Left axis: resistance of a Pt100. The right axis shows the same for a Pt1000 (everything × 10).
The orange line is the real curve per the standard. The grey dashed line is the commonly used straight line with α = 0.00385.
Example: 0 °C = 100.00 Ω, 100 °C = 138.51 Ω, 850 °C = 390.48 Ω (Pt1000: 3,904.8 Ω).
Up to 200 °C the two lines almost overlap. Above that the straight line drifts away: at 850 °C it is 36.8 Ω too high.

Line chart: resistance of a Pt100 against temperature from −200 to 850 °C per IEC 60751, with a second axis for Pt1000 and a dashed straight line with α = 0.00385 — **Fig. 3** Source: Own calculation per IEC 60751, 2026-11-02 ^{1, 2}

What does this mean for you? For a rough estimate between 0 and 100 °C (32–212 °F) the straight line is good enough. A controller that scales linearly above that range reads high.

Pt100 formula: resistance to temperature and back

The standard describes the curve with the Callendar–Van Dusen equation. Since the 2022 edition the formula itself is the specification; the numeric table in the standard is for information only ⁶. From 0 °C two coefficients are enough:

R (ϑ) = R_{0} \cdot (1 + A \cdot ϑ + B \cdot ϑ^{2})

Simply explained: 100 Ω times (1 + a small share per degree − an even smaller share per degree²). The B term is tiny but shows at high temperatures. That is why the curve bends slightly.

R(ϑ): resistance at temperature ϑ (often written t) in Ω
R₀: resistance at 0 °C: 100 Ω (Pt100) or 1,000 Ω (Pt1000)
ϑ: temperature in °C
A: 3.9083 × 10⁻³ °C⁻¹
B: −5.775 × 10⁻⁷ °C⁻²

Worked example

20 °C: 100 × (1 + 0.0039083 × 20 − 0.0000005775 × 400) = 100 × 1.07794 ≈ 107.79 Ω ².

Below 0 °C a third term with the coefficient C is added ^{1, 5}:

R (ϑ) = R_{0} \cdot [1 + A \cdot ϑ + B \cdot ϑ^{2} + C \cdot (ϑ - 100 °C) \cdot ϑ^{3}]

A, B: as above
C: −4.183 × 10⁻¹² °C⁻⁴, below 0 °C only

Worked example

−200 °C: the formula gives 18.52 Ω, the first value in the chart ².

Pt100 ohms to °C

If you have measured a resistance and need the temperature, rearrange the formula (valid from 0 °C):

ϑ = \frac{- A + \sqrt{A^{2} - 4 \cdot B \cdot (1 - \frac{R}{R_{0}})}}{2 \cdot B}

Simply explained: This formula turns a measured resistance back into a temperature. You don’t need to understand it, just plug in the value. Below 0 °C there is no closed solution; there you iterate (Newton’s method) or read the chart.

R: measured resistance in Ω
R₀, A, B: as above

Worked example

Your meter shows 110.00 Ω (Pt100): the sensor is at 25.68 °C (78.2 °F) ².

As an Excel formula

For English Excel, temperature in cell A2 or resistance in cell B2, Pt100, from 0 °C:

Resistance from temperature: =100*(1+3.9083E-3*A2-5.775E-7*A2^2)

Temperature from resistance: =(-3.9083E-3+SQRT(3.9083E-3^2-4*-5.775E-7*(1-B2/100)))/(2*-5.775E-7)

For a Pt1000 replace 100 with 1000. For °F, convert first: t °C = (t °F − 32) × 5/9.

Tolerance classes AA, A, B, C: how accurate is your sensor?

The standard defines four classes. Each has a fixed base at 0 °C plus a share that grows with the distance from 0 °C ^{1, 5}:

Δ ϑ = \pm (a + b \cdot | ϑ |)

Simply explained: A fixed base plus a share per degree. Every sensor is most accurate at 0 °C and gets coarser in both directions.

Δϑ: permitted deviation in °C
a: base: AA 0.1 · A 0.15 · B 0.3 · C 0.6 °C
b: share per degree: AA 0.0017 · A 0.002 · B 0.005 · C 0.01
|ϑ|: temperature in °C without its sign

Worked example

Class B at 100 °C: 0.3 + 0.005 × 100 = ±0.80 °C. In ohms that is 0.80 × 0.379 ≈ ±0.30 Ω, so you can check directly on the meter ².

How to read the chart

Left to right: temperature. Bottom to top: how many degrees a sensor of each class may be off.
Three lines: dark purple class AA, orange A, dark grey B. All are most accurate at 0 °C and get coarser in both directions.
Solid means the class applies here (wire-wound sensors). Dotted means there is no guarantee here. Class C is not shown because manufacturers state its valid range differently; the sensor data sheet applies.
Example: at 100 °C class AA may be off by ±0.27 °C, class B by ±0.80 °C – about three times as much.

Line chart: permitted deviation in degrees against temperature for Pt100 tolerance classes AA, A and B, valid range solid, outside dotted — **Fig. 4** Source: IEC 60751:2022, valid ranges per manufacturer documents, own chart, 2026-11-02 ^{1, 4, 5}

Class	Tolerance in °C	valid wire-wound	valid film (thin-film)
AA	±(0.1 + 0.0017·\|t\|)	−50 to 250 °C	0 to 150 °C
A	±(0.15 + 0.002·\|t\|)	−100 to 450 °C	−30 to 300 °C
B	±(0.3 + 0.005·\|t\|)	−196 to 600 °C	−50 to 500 °C
C	±(0.6 + 0.01·\|t\|)	not stated²	not stated²

Formulas per IEC 60751 ¹; ranges for AA, A, B per WIKA IN 00.17 ⁵, A and B also JUMO ⁴. ² The manufacturer documents we evaluated give no range for class C; the sensor data sheet then applies.

ASTM E1137: same curve, different tolerances

In the US, platinum RTDs are often specified to ASTM E1137. It uses the same curve as IEC 60751 (3850 ppm/K) but its own tolerances: Grade A ±(0.13 + 0.0017·|t|) °C, Grade B ±(0.25 + 0.0042·|t|) °C ¹⁷. At 100 °C that is ±0.30 or ±0.67 °C, against ±0.35 or ±0.80 °C to IEC ². So don’t treat Grade A/B as class A/B.

You may also meet other curves: the Japanese JPt100 (R100/R0 = 1.3916, withdrawn in 1989) ⁸ or a curve with α ≈ 0.00392. Their charts differ from the IEC curve by about 2 °C at 100 °C and about 6 °C at 300 °C ². Never mix a sensor of one curve with an input set to another.

How to read the image

Left: a thin-film element, a flat ceramic chip with the platinum film laid on top as a fine serpentine.
Right: a wire-wound element, a ceramic tube cut open to show a fine platinum coil inside.
Both are enlarged and not to scale. Each design has its own temperature range per class (table above).

Two platinum sensing elements side by side: left a flat ceramic chip with a serpentine platinum film, right a cut-open ceramic tube with a fine platinum coil — **Fig. 5** AI illustrationSource: shukchok, schematic, not to scale

Good to know about the classes

Since IEC 60751:2008 there are separate classes for the bare sensing element (W 0.1 to W 0.6, F 0.1 to F 0.6) and for the finished thermometer (AA to C) ⁶. W stands for wire-wound, F for film ⁵. For the finished thermometer the thermometer class applies at the connection end ³.

Terms such as “1/3 DIN” or “1/10 DIN” are manufacturer terms, not standard classes: a fraction of class B, defined at 0 °C only (1/3 DIN: ±0.1 °C, 1/10 DIN: ±0.03 °C). The standard class AA has made 1/3 DIN redundant ⁹.

2-wire, 3-wire, 4-wire: what the cable costs you

With a 2-wire hookup the instrument also measures the cable, out and back. Every ohm of lead counts as if the sensor were warmer. 3-wire and 4-wire hookups cancel out the lead resistance. For classes A and AA, according to Senmatic, the standard therefore requires three or four wires ³; WIKA calls 2-wire Pt100 hookups “not sensible” for these classes ⁵. IEC 60751:2022 covers connection types in section 5.5 ⁶.

R_{L} = \frac{ρ \cdot 2 \cdot l}{q}

Simply explained: Like a kitchen scale weighing the bowl too: without tare the result is wrong. You get the error in degrees by dividing R_L by the sensor slope (Pt100 at 0 °C: 0.391 Ω/°C).

R_L: resistance of both wires together in Ω
ρ: resistivity of copper at 20 °C: 0.017241 Ω·mm²/m [10]
l: cable length in m, one way (the 2 counts out and back)
q: conductor cross-section in mm²

Worked example

4 m (13 ft) of cable, assuming 0.22 mm²: 0.017241 × 2 × 4 / 0.22 ≈ 0.63 Ω. Divided by 0.391 Ω/°C that is +1.6 °C too high ².

How to read the chart

Left to right: cable length. Bottom to top: how many degrees too warm the sensor reads because of it.
Note: both axes jump in steps of ten (0.01 – 0.1 – 1 – 10 °C and 1 – 10 – 100 m). One step up means ten times as much.
Solid lines are Pt100, dashed lines Pt1000. Colour shows the wire size: orange 0.22 mm² (≈ AWG 24), dark purple 0.5 mm², grey 1.5 mm². The two dotted horizontal lines are the class A (0.15 °C) and B (0.30 °C) limits at 0 °C.
Example: 1 m (3 ft) of 0.22 mm² cable on a Pt100 adds about 0.4 °C – already beyond class B.
Each dashed Pt1000 line sits exactly one step of ten below its Pt100 line: ten times less error.

Chart with logarithmic axes: measurement error in degrees against cable length for Pt100 and Pt1000 at 0.22, 0.5 and 1.5 mm² wire size, with class A and B limits — **Fig. 6** Source: Own calculation, copper at 20 °C, slope at 0 °C per IEC 60751, 2026-11-02 ^{2, 10}

Cable length	0.22 mm² (≈ AWG 24)	0.5 mm²	1.5 mm²
1 m (3.3 ft)	0.40 °C (0.04 °C)	0.18 °C (0.02 °C)	0.06 °C (0.01 °C)
5 m (16 ft)	2.0 °C (0.20 °C)	0.88 °C (0.09 °C)	0.29 °C (0.03 °C)
10 m (33 ft)	4.0 °C (0.40 °C)	1.8 °C (0.18 °C)	0.59 °C (0.06 °C)

2-wire hookup, copper at 20 °C, sensor at 0 °C: error of a Pt100, Pt1000 in brackets. For comparison: class A allows 0.15 °C at 0 °C, class B 0.30 °C. Own calculation ².

Rule of thumb for a 2-wire Pt100 at 20 °C: about 0.4 °C per metre (0.12 °C per foot) of cable at 0.22 mm², about 0.18 °C per metre at 0.5 mm². A Pt1000 has a tenth of that. From just 0.37 m (Pt100) or 3.7 m (Pt1000), a 0.22 mm² lead alone uses up the whole class A tolerance at 0 °C; at 0.5 mm² the limit is 0.85 m or 8.5 m, at 1.5 mm² 2.6 m or 25.5 m ².

A worked example from our range: the PT100 temperature sensor and the PT100 screw-in probe 1/4″ are 2-wire with 4 m and 6 m of cable ¹¹. The catalogue does not state the wire size. Assuming 0.22 mm², they read +1.6 °C and +2.4 °C high, at 0.5 mm² +0.7 °C and +1.1 °C ². This offset is often stored in the controller.

What does this mean for you? When replacing a sensor, keep the same cable length and wire size, or set the offset again. With 2-wire: keep the lead short, choose a large wire size, use a Pt1000 instead of a Pt100 or trim out the lead resistance on the instrument.

How to test an RTD with a multimeter

1. Disconnect. Disconnect the sensor from the input and isolate the system.

2. Measure the resistance. Measure between the wires. Red and white are common; wires of the same colour belong to the same side of the element ^{5, 16}. Colours can differ between manufacturers, so check the data sheet when in doubt. With 3-wire sensors also measure the two same-coloured wires against each other: the result is roughly the lead resistance, close to 0 Ω.

3. Look up the target. Measure the ambient temperature and read the target value from the chart above. Example: 20 °C (68 °F) = 107.79 Ω.

4. Compare. Subtract the lead resistance and compare with the class limit in ohms. Class B at 20 °C: ±0.40 °C × 0.389 Ω/°C = ±0.16 Ω ².

5. Check the insulation. Test the insulation resistance between wire and sheath with an insulation tester. Test voltage and minimum value are in the sensor data sheet (how to read data sheets); the standard specifies this measurement at room temperature as a routine test ⁶.

The meter shows	Meaning
0 Ω	short circuit
∞ or “OL”	open circuit
about 1,000 Ω instead of about 100 Ω	a Pt1000 is fitted
reading changes when the cable is bent	broken wire
controller reading permanently too high	lead resistance not compensated

Mini study: how reliable are Pt100 charts on the web?

Most people use the first chart they find. We wanted to know whether you can rely on it, and checked freely available charts number by number against the standard ¹³.

Sample: 25 chart documents from 22 sources, 19 of them complete charts in 1 °C steps; about 17,300 values checked
Selection: Top results of German and US searches for “pt100 tabelle” and “pt100 resistance chart”, plus frequently linked PDFs
Updated: 2 November 2026
Limits: A sample, not representative of “the web”; charts published only as images were spot-checked; PDF extraction can lose cells, so gaps were checked one by one; missing trailing zeros (“140.4”) do not count as errors

Every number in a chart was checked against the target values of five variants: IEC 60751 rounded, IEC 60751 truncated, the old standard IEC 751:1983, the Japanese curve α = 0.003916 and a US curve α = 0.003926. Only temperatures where the variants differ are counted. Like a fingerprint, this shows which version a chart was calculated with ¹³.

Finding (19 complete 1 °C charts)	Charts	Share
correct (IEC 60751, rounded correctly, no single errors)	13	68 %
values per the old 1983 standard	3	16 %
with typos or transposed digits	5	26 %
at least one problem	6	32 %
systematically truncated instead of rounded	0	0 %

A chart can count in two rows. Own check, 2026-11-02 ¹³.

Chart	Error type	Wrong cells	Largest deviation
A	values per the old 1983 standard	– (throughout)	0.22 Ω at 850 °C (0.75 °C)
B	1983 values, plus transposed digits	2	about 27 Ω (≈ 79 °C)
C	1983 values, plus one value entered twice	1	about 0.4 Ω (≈ 1 °C)
D	typos, transposed digits and calculation errors	13	about 54 Ω (≈ 172 °C)
E	as D: the same chart as a web page	13 (the same)	about 54 Ω (≈ 172 °C)
F	one missing digit	1	about 140 Ω (over 300 °C)

17 wrong cells in 4 sources in total, from 0.03 Ω to 140 Ω. We do not name the publishers; the assignment is on file with the editors ¹³.

How to read the chart

Left to right: temperature. Bottom to top: the difference between an old 1983 table and today’s valid one, converted to degrees.
The orange line sits below zero: the old table gives a slightly lower resistance than the valid one (hence the axis title “difference old − new”, negative = old table gives fewer Ω).
The dashed dark purple line is the limit of the most accurate class AA.
Example: at 100 °C it is only −0.01 °C, at 300 °C −0.09 °C, but at 850 °C −0.75 °C.
Up to 250 °C the difference stays well within class AA. Only at high temperatures does it become noticeable.

Line chart: difference between a Pt100 chart per IEC 751:1983 and the valid IEC 60751 in degrees against temperature, with the class AA limit — **Fig. 7** Source: Own calculation, IEC 751:1983 vs IEC 60751:2022, 2026-11-02 ^{1, 2, 7}

The old values date from before the ITS-90 temperature scale: back then the resistance ratio at 100 °C was 1.3850, today it is 1.3851 ⁸. Up to 300 °C that makes less than 0.1 °C, 0.24 °C at 500 °C and 0.75 °C at 850 °C – mostly within class B, but not negligible for calibration work, class AA and high temperatures ². Typos are more dangerous: they sit in a single cell that the reader takes to be correct.

What does this mean for you? Only use charts from sources that state the standard and the calculation method. Check two control values: 100 °C = 138.51 Ω and 850 °C = 390.48 Ω. If they read 138.50 Ω and 390.26 Ω, the chart dates from 1983.

Pt100 or Pt1000?

Both follow the same curve. They differ in how sensitive they are to the cable and to the measuring current.

Feature	Pt100	Pt1000
Resistance at 0 °C	100 Ω	1,000 Ω
Lead error, 2-wire0.22 mm², per metre	about 0.4 °C ²	about 0.04 °C ² (advantage)
Recommended measuring currentagainst self-heating	max. 1 mA ¹²	max. 0.3 mA ¹²
Tolerance in °C	the same, by class ¹	the same, by class ¹
Input	must be set to Pt100	must be set to Pt1000

✓ = advantage on this feature. IEC 60751:2022 covers the measuring current in section 5.3 ⁶.

Good to know: myth and reality

Common assumption~~Any Pt100 chart will do.~~

In factSome charts still use the 1983 coefficients: 138.50 instead of 138.51 Ω at 100 °C and 390.26 instead of 390.48 Ω at 850 °C (−0.75 °C). In 19 charts we checked we also found 17 mistyped cells, up to 140 Ω off ^{1, 13}.

A sensor is judged wrongly at high temperature or in a single cell. Good sensors get replaced, bad ones stay in.

Common assumption~~A Pt100 is linear: R = 100 Ω × (1 + 0.00385 × t).~~

In factThe straight line is exact only at 0 °C and 100 °C. At 200 °C it is off by 1.1 Ω (≈ 3 °C), at 400 °C by 6.9 Ω (≈ 20 °C). The standard uses the squared term B and, below 0 °C, C ^{1, 2}.

Linear PLC scaling reads high at the upper end. Limits trip too early.

Common assumption~~The 0.00392 curve is the more accurate Pt100.~~

In factAlpha defines the curve (the purity of the platinum), not the accuracy; the tolerance class does that. Mixing curves gives about 2 °C error at 100 °C and about 6 °C at 300 °C ^{1, 2}.

A 0.00392 sensor on an input set to 0.00385 reads wrong all the time – an offset nobody can calibrate away at one point.

Common assumption~~A Pt100 is a PTC thermistor.~~

In factIt is a platinum RTD per IEC 60751 with an almost straight curve (+0.39 Ω/°C). It does have a positive temperature coefficient (PTC) ⁵, but it is no thermistor. PTC thermistors are semiconductor ceramics whose resistance jumps by several orders of magnitude at their switching temperature ¹⁴.

Wrong evaluation device: a PTC thermistor relay (motor protection) cannot read a Pt100, and vice versa.

Common assumption~~Class A applies up to 600 °C, class B up to 850 °C.~~

In factClass A applies only from −100 to 450 °C for wire-wound thermometers and from −30 to 300 °C for film elements. Class B applies up to 600 or 500 °C ^{4, 5}. Above 600 °C no class applies; other ranges must be marked separately by the manufacturer, for which IEC 60751:2022 introduces an extended marking ⁶.

Tolerance claims outside the valid range mean nothing. The actual deviation is not specified there.

Matching products

Both Pt100 sensors are 2-wire (worked example above). The TM63 contact thermometer measures with a built-in class B Pt1000; it does not read external Pt100 sensors ¹⁵.

PT100-Kabelfühler mit aufgewickeltem schwarzen PVC-Kabel und offenen Litzenenden in Rot und Blau/Weiß

Pt100 sensorPT100 Temperature SensorView product →

PT100-Einschraubfühler mit sechskantigem Gewindeanschluss und aufgewickeltem schwarzen PVC-Kabel

Pt100 screw-in probePT100 Screw-in Probe 1/4"View product →

Digital-Kontaktthermometer TM63 mit rundem Edelstahlgehäuse, roter LED-Anzeige '200°C' und drei Bedientasten

Contact thermometerDigital Contact Thermometer TM63View product →

RTD-Sensoren — Industriemarkt bei eazytech

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Temperaturmessgeräte — Industriemarkt bei eazytech

CategoryTemperature measuring devicesView category →

Frequently asked questions

What resistance should a Pt100 read at room temperature?

107.79 Ω at 20 °C (68 °F) and 109.73 Ω at 25 °C (77 °F). A Pt1000 reads 1,077.9 Ω and 1,097.3 Ω ².

How do I convert Pt100 ohms to °C?

From 0 °C with the rearranged Callendar–Van Dusen equation t = [−A + √(A² − 4·B·(1 − R/R₀))] / (2·B). Example: 110.00 Ω gives 25.68 °C. Below 0 °C you iterate or read the chart ^{1, 2}.

How do I test an RTD with a multimeter?

Disconnect the sensor, measure the resistance between the wires, measure the ambient temperature and compare with the chart value. Subtract the lead resistance first. Class B allows ±0.16 Ω at 20 °C ².

How can I tell if an RTD is bad?

0 Ω means a short circuit, ∞ or “OL” an open circuit, a reading that changes when the cable is bent a broken wire. About 1,000 Ω instead of about 100 Ω means a Pt1000 is fitted.

What does alpha 0.00385 mean?

Alpha is the average slope between 0 and 100 °C: (138.51 − 100) Ω divided by 100 Ω and 100 °C gives about 0.00385 per degree. It describes the curve, not the accuracy; the tolerance class does that ^{1, 2}.

What is the difference between Pt100 and Pt1000?

A Pt1000 has ten times the resistance at every temperature; the curve is the same. That makes it ten times less sensitive to the cable. It needs less measuring current (max. 0.3 mA instead of 1 mA) ^{2, 12}.

Is ASTM E1137 the same as IEC 60751?

Same curve (3850 ppm/K), different tolerances: ASTM Grade A ±(0.13 + 0.0017·|t|) °C and Grade B ±(0.25 + 0.0042·|t|) °C, against IEC class A ±(0.15 + 0.002·|t|) °C and class B ±(0.3 + 0.005·|t|) °C ^{1, 17}.

Can I download the Pt100 chart?

Yes, as CSV: 1,051 rows from −200 to 850 °C with tolerances in degrees and ohms, and a °F chart from −320 to 1,560 °F. For Excel, the formula is given above.

Sources

IEC 60751:2022 Industrial platinum resistance thermometers and platinum temperature sensors. Consulted: foreword, scope and table of contents [6]; coefficients, classes and ranges confirmed via [3, 4, 5].
shukchok: own calculation per IEC 60751, 2026-11-02 – resistance, slope and tolerance from −200 to 850 °C and in °F, straight-line approximation, 2-wire lead error, comparison with IEC 751:1983 and with a curve α ≈ 0.00392.
Senmatic A/S: Tolerance classes for sensors according to IEC 60751.
JUMO: Pt100 accuracy class (blog).
WIKA: Technical information IN 00.17 “Einsatzgrenzen und Genauigkeiten von Platin-Widerstandsthermometern nach DIN EN IEC 60751”, edition 11/2020 (p. 1 PTC, p. 2 designs W/F, p. 3 connection types and wire colours, p. 4 coefficients and class ranges).
IEC 60751:2022, edition 3.0, preview by VDE Verlag: foreword a) formula as specification, table for information only, d) extended marking, g) Annex A; sections 5.2 tolerance classes, 5.3 measuring current, 5.5 connection, 6.3.2 insulation resistance. Plus the preview of the 2008 edition (separate classes for sensing elements and thermometers).
IEC 751:1983 (withdrawn), Industrial platinum resistance thermometer sensors, temperature scale IPTS-68.
Yokogawa: FAQ on the Pt100 standards IPTS-68, ITS-90 and JPt100 (R100/R0 = 1.3850, 1.3851 and 1.3916).
Lapp: What is 1/3 DIN and 1/10 DIN?
IEC 60028:1925 International standard of resistance for copper (ρ = 0.017241 Ω·mm²/m at 20 °C).
shukchok.com: product pages PT100 temperature sensor (2-wire, 4 m) and PT100 screw-in probe 1/4″ (2-wire, 6 m), catalogue data of 2026-11-02; wire size and class are not stated there.
Yageo: general information on platinum thin-film sensors (data sheet appendix), section on measuring current and self-heating.
shukchok: mini study “How reliable are Pt100 charts on the web?”, 25 freely available chart documents from 22 sources, retrieved 2026-11-02; source list and individual findings are on file with the editors.
IEC 60738-1, Thermistors – Directly heated positive temperature coefficient – Part 1: Generic specification; EP 0454857 A1, paragraph 0004 (resistance of a PTC thermistor rising 10⁴- to 10⁷-fold at its switching temperature).
Nöding Messtechnik: data sheet Digital Contact Thermometer TM63 (Pt1000 class B).
JMS Southeast: RTD Wire, data sheet (“Conductors are color coded per ASTM E1137 & IEC 60751”).
TE Connectivity: FAQ platinum RTD sensors (ASTM E1137 and IEC 60751 both for 3850 ppm/K; Grade A/B tolerances).

How to cite this page

Scharff, A. (2026): Pt100 resistance chart and curve: −200 to 850 °C (with Pt1000). shukchok.com, Updated 14 November 2026. https://shukchok.com/en-sa/wissen/pt100-tabelle

Pt100 resistance chart and curve: −200 to 850 °C (with Pt1000)

Key terms in 30 seconds

Pt100 resistance chart (−200 to 850 °C)

Pt100 chart in °F

Pt1000 resistance table

Pt100 curve: why it is not quite straight

Pt100 formula: resistance to temperature and back

Pt100 ohms to °C

As an Excel formula

Tolerance classes AA, A, B, C: how accurate is your sensor?

ASTM E1137: same curve, different tolerances

Good to know about the classes

2-wire, 3-wire, 4-wire: what the cable costs you

How to test an RTD with a multimeter

Mini study: how reliable are Pt100 charts on the web?

Pt100 or Pt1000?

Good to know: myth and reality

Matching products

Frequently asked questions

Sources

How to cite this page

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