PT100 Table and RTD Calculator

The PT100 table is a free, browser-based tool that converts between temperature and resistance for platinum RTD sensors. Enter a temperature in °C or °F to get the resistance, or enter a resistance to get the temperature. It also builds a full table from −200 to 850 °C, so it works as an RTD PT100 table, a PT100 resistance table, or a PT100 resistance chart. It supports Pt100, Pt500 and Pt1000 sensors, shows the IEC 60751 tolerance band and a curve, and runs entirely in your browser with no sign-up. It also works on a phone.

It covers Pt100, Pt500 and Pt1000 sensors from −200 to 850 °C.

How to use the PT100 table

1. Choose the mode: temperature to resistance, or resistance to temperature.
2. Select the sensor type: Pt100 (100 Ω at 0 °C), Pt500 (500 Ω) or Pt1000 (1000 Ω).
3. Pick the unit you are working in, °C or °F.
4. Type your value into the input box. The results update as you type, so there is no separate calculate step.
5. Read the result, then check the tolerance band. It shows the allowed error in °C and in ohms, along with the sensitivity in Ω per °C at that temperature.
6. Open the calculation details to see the formula and each step with your numbers.
7. Set the table range and step (1, 5, 10 or 50 °C) to list values across the full range, and use the curve drawing to view the shape of the relationship.

Use Copy result to copy the result lines with a link, or Copy link to copy the page address. The address stores every input, so opening it later restores the same calculation. Print / save as PDF prints the inputs, results, calculation steps and the date.

The presets show a Pt100 at 100 °C and at −100 °C, a Pt1000 at 25 °C and 175.86 Ω converted back to temperature. Set the table step to 1, 5, 10 or 50 °C and the range you need, then print the table with Print / save as PDF.

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

A Pt100 has a nominal resistance of 100.000 Ω at 0 °C; that is what the 100 in the name means. At 100 °C it reads 138.506 Ω, which is the most common reference point people check when they build a table.

How do you convert PT100 resistance to temperature?

Above 0 °C, you solve the quadratic form of the IEC equation for t, which gives an exact answer. Below 0 °C, the cubic term makes this impossible to solve directly, so the calculator uses iteration to find the temperature. For example, a Pt100 reading of 175.86 Ω corresponds to 200.01 °C.

What is the Callendar–Van Dusen equation?

It is the standard equation in IEC 60751 that relates RTD resistance to temperature. Above 0 °C it is R(t) = R0 (1 + A t + B t²), with A = 3.9083 × 10⁻³ and B = −5.775 × 10⁻⁷. Below 0 °C a third term, C (t − 100) t³, is added, with C = −4.183 × 10⁻¹². R0 is the resistance at 0 °C, so for a Pt100 it is 100 Ω.

What is the difference between PT100 and PT1000?

Both are platinum RTDs that follow the same equation. The difference is R0: a Pt100 has 100 Ω at 0 °C, while a Pt1000 has 1000 Ω. Because every value scales with R0, a Pt1000 reads ten times the resistance of a Pt100 at the same temperature. At 25 °C, a Pt1000 reads about 1097.35 Ω.

What is PT100 class A and class B tolerance?

Class A and class B are tolerance classes in IEC 60751. Class A allows ±(0.15 + 0.002 |t|) °C, so about ±0.15 °C at 0 °C. Class B allows ±(0.3 + 0.005 |t|) °C, about ±0.3 °C at 0 °C. The allowed error grows with temperature, so at 100 °C the bands are about ±0.35 °C for class A and ±0.8 °C for class B.

Why use a 3-wire or 4-wire RTD?

In a 2-wire connection, the resistance of the lead wires adds to the reading, which causes an error that grows with cable length. A 3-wire or 4-wire connection compensates for this lead resistance. A 4-wire connection is the most accurate of the three because it separates the current path from the voltage measurement.

Sources

Checked October 2026:

• Fluke Pt100 table generator: IEC 60751 Callendar–Van Dusen coefficients A = 3.9083 × 10⁻³, B = −5.775 × 10⁻⁷, C = −4.183 × 10⁻¹²
• KP-AS Pt100 resistance table (all 106 points match to 0.005 Ω)
• Lapp, Pt100 accuracy classes: class tolerances and their temperature ranges
• Pt500 and Pt1000 use the same equation scaled by R0

For estimation; verify critical designs against the applicable standard.

Worked examples

Calculated by the tool above with these values.

Frequently asked questions

Is the PT100 table free to use?

Yes. It runs in your browser with no sign-up, and nothing you enter is uploaded.

Can I use the results in commercial work?

Yes. You can use the results in designs, quotes, documentation and reports without attribution.

Can I use a Pt500 or Pt1000 instead of a Pt100?

Yes. Select Pt500 (500 Ω at 0 °C) or Pt1000 (1000 Ω at 0 °C) as the sensor type, and the same equation is applied with that R0.

Does the table work on a phone?

Yes. The tool works on phones as well as desktop browsers.

What is the resistance of a PT1000 at 0 °C?

Exactly 1000 Ω. Every value is ten times the Pt100 value at the same temperature.

How much does a PT100 change per degree?

About 0.385 Ω per °C on average between 0 and 100 °C (38.5 Ω over 100 °C). The tool shows the exact sensitivity at your temperature.

Can I enter the temperature in °F?

Yes. Choose °F as the temperature unit; 212 °F gives 138.506 Ω on a Pt100.

What is the resistance of a PT100 at −50 °C?

Look it up in the table or enter −50 in the tool; below 0 °C the extra C term of the Callendar–Van Dusen equation is applied automatically.

Related tools

• Thermocouple table: use this when your sensor is a thermocouple rather than an RTD.
• 4-20 mA calculator: use this to convert a 4-20 mA signal from a transmitter into a scaled value.
• IP rating chart: use this to check the ingress protection rating of an enclosure for a sensor installation.
• Resistor color code calculator: use this to read or check the value of a resistor from its color bands.
• PLC simulator: use this to test control logic that reads a temperature signal.
• All calculators: use this to browse every calculator on the site.