Reference · updated 10 November 2026

PT100 resistance table: -200 to 850 °C

Q: What is the resistance of a PT100 at 0 °C and at 100 °C?

100.00 Ω at 0 °C and 138.51 Ω at 100 °C. At 200 °C it is 175.86 Ω, and at −100 °C it is 60.26 Ω.

Q: How do I convert PT100 ohms to temperature?

Look the measured resistance up in the table and read the temperature in the left column. Between two rows, interpolate in a straight line; over a 5 °C step the error from that is far below the tolerance of the sensor. Subtract the lead resistance first, or zero the leads with REL.

Q: What is the difference between PT100 Class A and Class B?

Class A is the tighter tolerance: ± (0.15 + 0.002 × |t|) °C, so ±0.15 °C at 0 °C. Class B is ± (0.30 + 0.005 × |t|) °C, so ±0.30 °C at 0 °C. The second table also shows the temperature ranges where each class applies.

Q: Why does my PT100 read too high on a multimeter?

The usual causes are the resistance of the test leads and of a long two-wire cable, a sensor that is warmer than you think, and a sensor that is still connected to other electronics. Zero the leads with REL, disconnect the sensor, and let it settle.

A Pt100 is a platinum resistance sensor that reads exactly 100.00 Ω at 0 °C and rises by about 0.39 Ω per °C. To get a temperature from it, measure its resistance and look the value up. This page has the table for −200 to 850 °C in 5 °C steps, the equation behind it, and the tolerance of the sensor. Every value is calculated from the IEC 60751 equation when the page is built; none is typed in by hand, and the build stops if four reference values are off.

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PT100 resistance table

Find the row nearest your reading, or interpolate between two rows. The table is for the standard sensor with α = 0.00385 (the one most "Pt100" parts are). Negative temperatures are marked with a minus sign.

Pt100 resistance in ohms, −200 to 850 °C in 5 °C steps (IEC 60751)
Temperature (°C)	Resistance (Ω)
−200	18.52
−195	20.68
−190	22.83
−185	24.97
−180	27.10
−175	29.22
−170	31.34
−165	33.44
−160	35.54
−155	37.64
−150	39.72
−145	41.80
−140	43.88
−135	45.94
−130	48.00
−125	50.06
−120	52.11
−115	54.15
−110	56.19
−105	58.23
−100	60.26
−95	62.28
−90	64.30
−85	66.31
−80	68.33
−75	70.33
−70	72.33
−65	74.33
−60	76.33
−55	78.32
−50	80.31
−45	82.29
−40	84.27
−35	86.25
−30	88.22
−25	90.19
−20	92.16
−15	94.12
−10	96.09
−5	98.04
0	100.00
5	101.95
10	103.90
15	105.85
20	107.79
25	109.73
30	111.67
35	113.61
40	115.54
45	117.47
50	119.40
55	121.32
60	123.24
65	125.16
70	127.08
75	128.99
80	130.90
85	132.80
90	134.71
95	136.61
100	138.51
105	140.40
110	142.29
115	144.18
120	146.07
125	147.95
130	149.83
135	151.71
140	153.58
145	155.46
150	157.33
155	159.19
160	161.05
165	162.91
170	164.77
175	166.63
180	168.48
185	170.33
190	172.17
195	174.02
200	175.86
205	177.69
210	179.53
215	181.36
220	183.19
225	185.01
230	186.84
235	188.66
240	190.47
245	192.29
250	194.10
255	195.91
260	197.71
265	199.51
270	201.31
275	203.11
280	204.90
285	206.70
290	208.48
295	210.27
300	212.05
305	213.83
310	215.61
315	217.38
320	219.15
325	220.92
330	222.68
335	224.45
340	226.21
345	227.96
350	229.72
355	231.47
360	233.21
365	234.96
370	236.70
375	238.44
380	240.18
385	241.91
390	243.64
395	245.37
400	247.09
405	248.81
410	250.53
415	252.25
420	253.96
425	255.67
430	257.38
435	259.08
440	260.78
445	262.48
450	264.18
455	265.87
460	267.56
465	269.25
470	270.93
475	272.61
480	274.29
485	275.97
490	277.64
495	279.31
500	280.98
505	282.64
510	284.30
515	285.96
520	287.62
525	289.27
530	290.92
535	292.56
540	294.21
545	295.85
550	297.49
555	299.12
560	300.75
565	302.38
570	304.01
575	305.63
580	307.25
585	308.87
590	310.49
595	312.10
600	313.71
605	315.31
610	316.92
615	318.52
620	320.12
625	321.71
630	323.30
635	324.89
640	326.48
645	328.06
650	329.64
655	331.22
660	332.79
665	334.36
670	335.93
675	337.50
680	339.06
685	340.62
690	342.18
695	343.73
700	345.28
705	346.83
710	348.38
715	349.92
720	351.46
725	353.00
730	354.53
735	356.06
740	357.59
745	359.12
750	360.64
755	362.16
760	363.67
765	365.19
770	366.70
775	368.21
780	369.71
785	371.21
790	372.71
795	374.21
800	375.70
805	377.19
810	378.68
815	380.17
820	381.65
825	383.13
830	384.60
835	386.08
840	387.55
845	389.02
850	390.48

Tolerance classes

The table gives the nominal resistance. A real sensor may differ from it by the tolerance of its class in IEC 60751. The limit is ± (a + b × |t|) in °C, where t is the temperature of the sensor.

Pt100 tolerance classes A and B (IEC 60751)
Class	Tolerance	At 0 °C (± °C)	At 100 °C (± °C)	Range, wire-wound	Range, thin-film
A	± (0.15 + 0.002 × \|t\|) °C	± 0.15	± 0.35	−100 … 450 °C	−30 … 300 °C
B	± (0.30 + 0.005 × \|t\|) °C	± 0.30	± 0.80	−196 … 600 °C	−50 … 500 °C

Class B is the common grade and Class A is the tighter one. The ranges show where each class applies; outside them the standard gives no class. Many probes are sold as "1/3 DIN" or similar: those fractions are not in the standard, so read the data sheet of your probe for what the maker promises.

How the numbers are calculated

IEC 60751 describes the resistance of a platinum sensor with the Callendar–Van Dusen equation. With R0 = 100 Ω at 0 °C, A = 3.9083 × 10⁻³, B = −5.775 × 10⁻⁷ and C = −4.183 × 10⁻¹²:

t ≥ 0 °C: R = R0 × (1 + A·t + B·t²)

t < 0 °C: R = R0 × (1 + A·t + B·t² + C·(t − 100)·t³)

Four values to check against any other chart: 100.00 Ω at 0 °C, 138.51 Ω at 100 °C, 175.86 Ω at 200 °C and 60.26 Ω at −100 °C. The generator for this page checks exactly these four before it builds.

The table is the sensor's resistance, not a temperature measurement by itself. A meter measuring resistance adds the resistance of its leads and of the sensor wiring; see the next sections.

How to use the table with a multimeter

Disconnect the sensor from its transmitter or controller, so nothing else is in parallel with it.
Set the multimeter to ohms. A Pt100 reads between about 18 Ω and 390 Ω over its range, so a range up to 600 Ω or auto range is right.
Short the two probes together and press REL, so the resistance of the leads is taken off every later reading. Without this, a 0.4 Ω pair of test leads adds about 1 °C of error.
Connect the probes to the two sensor wires, wait until the reading is steady, and look it up in the table. Between two rows, interpolate: near 100 °C one °C is 0.39 Ω.

A two-wire sensor includes the resistance of its own cable in the reading. For a three-wire or four-wire sensor you can measure the cable resistance between the two wires that are joined at the sensor, and subtract it. Do not measure a sensor while it is connected to a live circuit.

Self-heating can matter too: a meter sends a small current through the sensor, and a sensor in still air warms a little. Read it quickly and with the same range each time.

Worked examples

Reading to temperature. A sensor reads 109.73 Ω. The table has 109.73 Ω on the 25 °C row, so the sensor is at 25 °C. The bath is at room temperature, which fits.

Leads and interpolation. You short the test leads and the meter shows 0.40 Ω. Measuring the probe, it shows 139.00 Ω. Correct for the leads: 139.00 − 0.40 = 138.60 Ω. The table has 138.51 Ω at 100 °C and 140.40 Ω at 105 °C, 0.39 Ω per °C. So (138.60 − 138.51) ÷ 0.39 ≈ 0.2, and the temperature is about 100.2 °C. Without the lead correction you would have read 101.3 °C, more than a degree too high.

Read this live with a meter

To read a Pt100 and see the result in the app, connect a Bluetooth multimeter the app reads live, such as the OWON OW18B, and set it to ohms. The big readout shows the resistance with stable digits, and REL zeroes the leads as above. To follow a sensor while it cools or warms, record a time series and review the graph afterwards.

The calculator in the app has preset formulas for Ohm's law and power, series and parallel, dividers, LED resistors, RC, dB and unit conversion, and Cal Box fills it from your live reading and recent captures. The app does not have a Pt100 table of its own today; this page is the reference. For a thermocouple instead of a resistance sensor, see the type K thermocouple table.

Sources

IEC 60751, industrial platinum resistance thermometers: the equation and the constants A, B and C. The constants are also printed in the Wikipedia article Resistance thermometer (read 2026-11-10).
Tolerance classes A and B with their formulas and ranges: GHI Tolerance classes Pt100 (read 2026-11-10; the standard itself was not read).

What the app does here, and what it doesn't

What it does
What it does	Plan
A large readout that shows which digits have settled; OL and UL are shown as OL and UL, never as a number.	Free
REL shows the difference from a stored reference, for example to null out test-lead resistance.	Free
Log sessions hold captures and time-series recordings, and recording continues with the screen locked.	Free
Presets for Ohm's law and power, series and parallel, dividers, LED resistors, RC, dB and unit conversion.	Free
Cal Box fills the calculator from your live reading and recent captures, and suggests Ohm's law.	Free

Questions

What is the resistance of a PT100 at 0 °C and at 100 °C?

100.00 Ω at 0 °C and 138.51 Ω at 100 °C. At 200 °C it is 175.86 Ω, and at −100 °C it is 60.26 Ω.

How do I convert PT100 ohms to temperature?

Look the measured resistance up in the table and read the temperature in the left column. Between two rows, interpolate in a straight line; over a 5 °C step the error from that is far below the tolerance of the sensor. Subtract the lead resistance first, or zero the leads with REL.

What is the difference between PT100 Class A and Class B?

Class A is the tighter tolerance: ± (0.15 + 0.002 × |t|) °C, so ±0.15 °C at 0 °C. Class B is ± (0.30 + 0.005 × |t|) °C, so ±0.30 °C at 0 °C. The second table also shows the temperature ranges where each class applies.

Why does my PT100 read too high on a multimeter?

The usual causes are the resistance of the test leads and of a long two-wire cable, a sensor that is warmer than you think, and a sensor that is still connected to other electronics. Zero the leads with REL, disconnect the sensor, and let it settle.

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