Temperature Measurement · Glossary

What is Pt100?

100 Ω at 0 °CTemperature Measurement

Pt100 is a platinum RTD with a resistance of 100 Ω at 0 °C, following the IEC 60751 resistance curve.

Pt100 Explained

The Callendar Van Dusen equation in IEC 60751 gives the Pt100 resistance at any temperature. Above 0 °C only the A and B coefficients are used; below 0 °C a C term is added.

The average slope is about 0.385 Ω per °C between 0 and 100 °C.

Pt100 Formula

R_t = R₀ × (1 + A t + B t²) for t ≥ 0 °C

R₀	100 Ω
A	3.9083 × 10⁻³ °C⁻¹
B	−5.775 × 10⁻⁷ °C⁻²
t	temperature (°C)

Example: At 100 °C: R = 100 × (1 + 0.39083 − 0.005775) = 138.51 Ω.

Calculators for Pt100

CalculatorPt100 TableFree online calculator with formula and worked example.CalculatorRTD CalculatorFree online calculator with formula and worked example.CalculatorTemperature Transmitter CalculatorFree online calculator with formula and worked example.

Free Downloads

Free downloadTemperature Measurement Cheat SheetFree printable PDF cheat sheet.Free downloadTemperature Transmitter Calibration Report FormatFree download in Excel and PDF.

Frequently Asked Questions

What is Pt100?

Pt100 is a platinum RTD with a resistance of 100 Ω at 0 °C, following the IEC 60751 resistance curve.

What is the C coefficient?

C = −4.183 × 10⁻¹² °C⁻⁴, used with an extra term for temperatures below 0 °C.

How do I check a Pt100 with a multimeter?

Measure resistance and compare with the table; about 109.7 Ω at 25 °C. Subtract lead resistance for 2 wire measurements.

Learn more on the blog

What is an RTD and how it works

A practical guide on instrumentationblog.in with more detail on Pt100 and how it is applied on real plants.

Read Full Article

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