What is the formula for PT100 / PT1000 RTD Converter?

Core formula: R(T) = R0[1 + A·T + B·T² (+ C(T−100)T³)], A = 3.9083e−3. The tool returns results instantly using this formula and the selected parameters.

PT100 / PT1000 RTD Converter

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Two-way platinum resistance conversion per IEC 60751 (Callendar–Van Dusen), with sensitivity and lead-resistance error estimates.

Key points

PT100 / PT1000 RTD Converter: Two-way platinum resistance conversion per IEC 60751 (Callendar–Van Dusen), with sensitivity and lead-resistance error estimates. Formula: R(T) = R0[1 + A·T + B·T² (+ C(T−100)T³)], A = 3.9083e−3. Enter parameters on the DD-CAT IDE online tool page to get results instantly, with a calculation-model diagram that updates with the inputs. PT100 reads 100Ω at 0°C, 138.51Ω at 100°C and 60.26Ω at −100°C — handy for a quick sanity check. In two-wire mode every ohm of lead is worth about 2.6°C; three-wire needs matched leads and four-wire is the most accurate.

Inputs

R(T) = R0[1 + A·T + B·T² (+ C(T−100)T³)], A = 3.9083e−3

Calculation model (updates with parameters)

PT100 Resistance	138.5055 Ω
Temperature / resistance	100.000 ℃ ↔ 138.5055 Ω
Sensitivity dR/dT	0.3793 Ω/℃	0.3908Ω/°C at 0°C for PT100
Change from 0°C	38.5055 Ω
Lead-resistance error	Not included (ideal 4-wire)

Engineering notes

PT100 reads 100Ω at 0°C, 138.51Ω at 100°C and 60.26Ω at −100°C — handy for a quick sanity check.
In two-wire mode every ohm of lead is worth about 2.6°C; three-wire needs matched leads and four-wire is the most accurate.

FAQ

What is PT100 / PT1000 RTD Converter for?: Two-way platinum resistance conversion per IEC 60751 (Callendar–Van Dusen), with sensitivity and lead-resistance error estimates.
What is the formula for PT100 / PT1000 RTD Converter?: Core formula: R(T) = R0[1 + A·T + B·T² (+ C(T−100)T³)], A = 3.9083e−3. The tool returns results instantly using this formula and the selected parameters.
What engineering notes should I keep in mind when using PT100 / PT1000 RTD Converter?: PT100 reads 100Ω at 0°C, 138.51Ω at 100°C and 60.26Ω at −100°C — handy for a quick sanity check. In two-wire mode every ohm of lead is worth about 2.6°C; three-wire needs matched leads and four-wire is the most accurate.