100Ω Platinum — the Industrial Standard
A PT100 is a platinum resistance thermometer with a nominal resistance of 100.00 Ω at 0 °C and a defined temperature coefficient of resistance (TCR) of α = 0.003851 Ω/Ω/°C (commonly rounded to 0.00385). The α-value is averaged between 0 °C and 100 °C and is the property that distinguishes the IEC industrial curve from the (less common) ITS-90 SPRT curve.
Because platinum's resistance change with temperature is highly reproducible, well-characterized, and nearly linear, the PT100 is the most widely deployed precision temperature sensor in industry. All values on this page are referenced to the International Temperature Scale of 1990 (ITS-90) and conform to IEC 60751:2008 and ASTM E1137.
Key Characteristics
- Nominal resistance: R₀ = 100.00 Ω at 0 °C
- Temperature coefficient: α = 0.00385 Ω/Ω/°C
- Operating range: -200 °C to +850 °C
- Sensitivity at 0 °C: ~0.385 Ω/°C
- Long-term drift: typically < 0.04 °C/year at 200 °C
- Self-heating: ~0.05 °C at 1 mA excitation in still air
How to Use This Table
For any temperature t in the left column, the corresponding resistance value R(t) is the nominal output of a perfect (zero-tolerance) PT100. The right columns give the maximum allowable deviation in °C for Class A and Class B sensors per IEC 60751.
Need PT1000?
Multiply every resistance value by 10. A PT1000 has R₀ = 1000.00 Ω at 0 °C, the same TCR, the same tolerance percentages, and follows the same Callendar-Van Dusen equation with R₀ = 1000.
Quick Reference Points
-200 °C → 18.52 Ω
-100 °C → 60.26 Ω
0 °C → 100.00 Ω
+100 °C → 138.51 Ω
+200 °C → 175.86 Ω
+400 °C → 247.09 Ω
+600 °C → 313.71 Ω
+850 °C → 390.48 Ω
Class A, Class B & 1/3 DIN per IEC 60751
IEC 60751 defines tolerance bands as a fixed offset plus a slope that grows with the magnitude of the measured temperature. The narrower the band, the tighter the conformance to the nominal R(t) curve — and the higher the cost of the sensing element.
| Class | Tolerance Formula (°C) | At 0 °C | At 100 °C | At 400 °C | At 850 °C |
|---|---|---|---|---|---|
| Class AA (1/3 DIN) | ±(0.10 + 0.0017·|t|) | ±0.10 | ±0.27 | ±0.78 | n/a (Class A limit) |
| Class A | ±(0.15 + 0.002·|t|) | ±0.15 | ±0.35 | ±0.95 | ±1.85 |
| Class B | ±(0.30 + 0.005·|t|) | ±0.30 | ±0.80 | ±2.30 | ±4.55 |
| Class C | ±(0.60 + 0.010·|t|) | ±0.60 | ±1.60 | ±4.60 | ±9.10 |
Notes on Class AA / 1/3 DIN
"1/3 DIN" or "Class AA" tolerance is approximately one-third of the Class B tolerance — and is only specified between -50 °C and +250 °C for wire-wound elements (or -100 °C to +450 °C for thin-film). Above those temperatures the element reverts to Class A behavior. For metrology-grade work below ±0.1 °C, use a 4-wire SPRT calibrated at the ITS-90 fixed points instead.
The Callendar-Van Dusen Equation
The platinum R(t) curve is defined piecewise by the Callendar-Van Dusen equation. Above 0 °C the curve is a second-order polynomial; below 0 °C a small cubic correction term is added.
| Constant | Value | Units |
|---|---|---|
| A | 3.9083 × 10⁻³ | °C⁻¹ |
| B | -5.775 × 10⁻⁷ | °C⁻² |
| C (used only for t < 0 °C) | -4.183 × 10⁻¹² | °C⁻⁴ |
| α (0–100 °C average TCR) | 3.851 × 10⁻³ | Ω/Ω/°C |
Inverse Calculation (Resistance → Temperature)
For t ≥ 0 °C, solve the quadratic directly: t = ( -A + √(A² − 4B(1 − R/R₀)) ) / (2B). For t < 0 °C, the cubic term forces an iterative or look-up-table solution — Thermometrics calibration software uses a 64-point cubic-spline inverse with a quoted accuracy of < 0.005 °C across the full range.
PT100 R(t) from -200 °C to +850 °C
Resistance is given in ohms; tolerance values are the maximum allowable deviation from nominal R(t), expressed in °C. Per IEC 60751:2008. Increments of 10 °C; for 1 °C intervals contact our applications team.
| Temperature (°C) | Resistance (Ω) | Class A Tol (°C) | Class B Tol (°C) |
|---|---|---|---|
| -200 | 18.52 | ±0.550 | ±1.300 |
| -190 | 22.83 | ±0.530 | ±1.250 |
| -180 | 27.10 | ±0.510 | ±1.200 |
| -170 | 31.34 | ±0.490 | ±1.150 |
| -160 | 35.54 | ±0.470 | ±1.100 |
| -150 | 39.72 | ±0.450 | ±1.050 |
| -140 | 43.88 | ±0.430 | ±1.000 |
| -130 | 48.00 | ±0.410 | ±0.950 |
| -120 | 52.11 | ±0.390 | ±0.900 |
| -110 | 56.19 | ±0.370 | ±0.850 |
| -100 | 60.26 | ±0.350 | ±0.800 |
| -90 | 64.30 | ±0.330 | ±0.750 |
| -80 | 68.33 | ±0.310 | ±0.700 |
| -70 | 72.33 | ±0.290 | ±0.650 |
| -60 | 76.33 | ±0.270 | ±0.600 |
| -50 | 80.31 | ±0.250 | ±0.550 |
| -40 | 84.27 | ±0.230 | ±0.500 |
| -30 | 88.22 | ±0.210 | ±0.450 |
| -20 | 92.16 | ±0.190 | ±0.400 |
| -10 | 96.09 | ±0.170 | ±0.350 |
| +0 | 100.00 | ±0.150 | ±0.300 |
| +10 | 103.90 | ±0.170 | ±0.350 |
| +20 | 107.79 | ±0.190 | ±0.400 |
| +30 | 111.67 | ±0.210 | ±0.450 |
| +40 | 115.54 | ±0.230 | ±0.500 |
| +50 | 119.40 | ±0.250 | ±0.550 |
| +60 | 123.24 | ±0.270 | ±0.600 |
| +70 | 127.08 | ±0.290 | ±0.650 |
| +80 | 130.90 | ±0.310 | ±0.700 |
| +90 | 134.71 | ±0.330 | ±0.750 |
| +100 | 138.51 | ±0.350 | ±0.800 |
| +110 | 142.29 | ±0.370 | ±0.850 |
| +120 | 146.07 | ±0.390 | ±0.900 |
| +130 | 149.83 | ±0.410 | ±0.950 |
| +140 | 153.58 | ±0.430 | ±1.000 |
| +150 | 157.33 | ±0.450 | ±1.050 |
| +160 | 161.05 | ±0.470 | ±1.100 |
| +170 | 164.77 | ±0.490 | ±1.150 |
| +180 | 168.48 | ±0.510 | ±1.200 |
| +190 | 172.17 | ±0.530 | ±1.250 |
| +200 | 175.86 | ±0.550 | ±1.300 |
| +210 | 179.53 | ±0.570 | ±1.350 |
| +220 | 183.19 | ±0.590 | ±1.400 |
| +230 | 186.84 | ±0.610 | ±1.450 |
| +240 | 190.47 | ±0.630 | ±1.500 |
| +250 | 194.10 | ±0.650 | ±1.550 |
| +260 | 197.71 | ±0.670 | ±1.600 |
| +270 | 201.31 | ±0.690 | ±1.650 |
| +280 | 204.90 | ±0.710 | ±1.700 |
| +290 | 208.48 | ±0.730 | ±1.750 |
| +300 | 212.05 | ±0.750 | ±1.800 |
| +310 | 215.61 | ±0.770 | ±1.850 |
| +320 | 219.15 | ±0.790 | ±1.900 |
| +330 | 222.68 | ±0.810 | ±1.950 |
| +340 | 226.21 | ±0.830 | ±2.000 |
| +350 | 229.72 | ±0.850 | ±2.050 |
| +360 | 233.21 | ±0.870 | ±2.100 |
| +370 | 236.70 | ±0.890 | ±2.150 |
| +380 | 240.18 | ±0.910 | ±2.200 |
| +390 | 243.64 | ±0.930 | ±2.250 |
| +400 | 247.09 | ±0.950 | ±2.300 |
| +410 | 250.53 | ±0.970 | ±2.350 |
| +420 | 253.96 | ±0.990 | ±2.400 |
| +430 | 257.38 | ±1.010 | ±2.450 |
| +440 | 260.78 | ±1.030 | ±2.500 |
| +450 | 264.18 | ±1.050 | ±2.550 |
| +460 | 267.56 | ±1.070 | ±2.600 |
| +470 | 270.93 | ±1.090 | ±2.650 |
| +480 | 274.29 | ±1.110 | ±2.700 |
| +490 | 277.64 | ±1.130 | ±2.750 |
| +500 | 280.98 | ±1.150 | ±2.800 |
| +510 | 284.30 | ±1.170 | ±2.850 |
| +520 | 287.62 | ±1.190 | ±2.900 |
| +530 | 290.92 | ±1.210 | ±2.950 |
| +540 | 294.21 | ±1.230 | ±3.000 |
| +550 | 297.49 | ±1.250 | ±3.050 |
| +560 | 300.75 | ±1.270 | ±3.100 |
| +570 | 304.01 | ±1.290 | ±3.150 |
| +580 | 307.25 | ±1.310 | ±3.200 |
| +590 | 310.49 | ±1.330 | ±3.250 |
| +600 | 313.71 | ±1.350 | ±3.300 |
| +610 | 316.92 | ±1.370 | ±3.350 |
| +620 | 320.12 | ±1.390 | ±3.400 |
| +630 | 323.30 | ±1.410 | ±3.450 |
| +640 | 326.48 | ±1.430 | ±3.500 |
| +650 | 329.64 | ±1.450 | ±3.550 |
| +660 | 332.79 | ±1.470 | ±3.600 |
| +670 | 335.93 | ±1.490 | ±3.650 |
| +680 | 339.06 | ±1.510 | ±3.700 |
| +690 | 342.18 | ±1.530 | ±3.750 |
| +700 | 345.28 | ±1.550 | ±3.800 |
| +710 | 348.38 | ±1.570 | ±3.850 |
| +720 | 351.46 | ±1.590 | ±3.900 |
| +730 | 354.53 | ±1.610 | ±3.950 |
| +740 | 357.59 | ±1.630 | ±4.000 |
| +750 | 360.64 | ±1.650 | ±4.050 |
| +760 | 363.67 | ±1.670 | ±4.100 |
| +770 | 366.70 | ±1.690 | ±4.150 |
| +780 | 369.71 | ±1.710 | ±4.200 |
| +790 | 372.71 | ±1.730 | ±4.250 |
| +800 | 375.70 | ±1.750 | ±4.300 |
| +810 | 378.68 | ±1.770 | ±4.350 |
| +820 | 381.65 | ±1.790 | ±4.400 |
| +830 | 384.60 | ±1.810 | ±4.450 |
| +840 | 387.55 | ±1.830 | ±4.500 |
| +850 | 390.48 | ±1.850 | ±4.550 |
Using This Table for PT1000 Sensors
A PT1000 is electrically identical to a PT100 except that the nominal resistance is scaled by a factor of 10. Every value in the resistance column above is multiplied by 10, giving R₀ = 1000.00 Ω at 0 °C and a sensitivity of approximately 3.85 Ω/°C at the ice point. Class A and Class B tolerance percentages — and therefore the °C tolerance columns — are unchanged.
PT1000 sensors are commonly used in HVAC controls, building automation, and battery-powered field instruments. The ten-fold higher resistance reduces the effect of lead-wire resistance, which can otherwise be a dominant error source in 2-wire installations.
Worked PT1000 Example
A PT1000 reads 1138.51 Ω. Divide by 10 to get 113.851 Ω-equivalent on the PT100 table → matches +100 °C exactly. Class B tolerance at that point is ±0.80 °C, so the true temperature lies between +99.2 and +100.8 °C.
2-Wire Lead Compensation
For a PT100 with 10 Ω of total lead resistance, the reading is biased by approximately +26 °C. The same lead resistance on a PT1000 biases by only ~+2.6 °C — still significant, but ten times smaller.
Ready to Spec
Your Sensor?
Whether you need a standard catalog configuration or a fully custom engineered assembly, our technical team responds to all quote requests within one business day.