Thermistor Resistance to Temperature Calculator
Measured a sensor and got a resistance? Turn it into a temperature with the sensor’s Beta value, its Steinhart–Hart coefficients, or three points from its data sheet.
Method reviewed October 26, 2026. Version 1.0.0. How it works
Result
- Temperature
- 122°F
3,602 Ω ≈ 122 °F (50 °C).
- Temperature in kelvin
- 323.2K
- Steinhart–Hart A
- 0.001
- Steinhart–Hart B
- 0
- Steinhart–Hart C
- 0
Show the working
- Fit 1/T = A + B ln R + C (ln R)³ through the three pointsA = 1.125547e-3, B = 2.347041e-4, C = 8.545186e-8
- Steinhart–Hart: 1/T = A + B ln R + C (ln R)³ln R = 8.18924; 1/T = 3.094526e-3 K⁻¹
- T = 1 ÷ (1/T), then convert from kelvin323.2 K = 122 °F
Three ways to describe a thermistor
- Three data-sheet points: the calculator fits the Steinhart–Hart equation through them. This is the most accurate option when your sensor’s resistance table is available.
- Steinhart–Hart coefficients: 1/T = A + B ln R + C (ln R)³, with T in kelvin and R in ohms.
- Beta value: 1/T = 1/T₀ + ln(R/R₀) ÷ B, using the resistance at 25 °C. Simple, but accurate only over a narrow range.
How accurate is it?
Vishay states that the Steinhart–Hart equation fitted through three points is typically within ±0.15 °C over −50 °C to +150 °C, and much better within a 100 °C span. With three points from Vishay’s 10 kΩ Curve 1 table (0, 25 and 70 °C), this calculator predicts the table’s 50 °C value to within 0.002 °C.
The sensor’s own tolerance usually matters more: a 1 % resistance tolerance is roughly a quarter of a degree near room temperature.
Worked example
These are the example values the calculator opens with, and the result the engine calculates for them.
Inputs
- Sensor data I have
- Three resistance–temperature points (most accurate)
- Measured resistance
- 3,602 Ω
- Point 1 temperature
- 32 °F
- Point 1 resistance
- 32,660 Ω
- Point 2 temperature
- 77 °F
- Point 2 resistance
- 10,000 Ω
- Point 3 temperature
- 158 °F
- Point 3 resistance
- 1,753 Ω
Result
- Temperature
- 122 °F
- Temperature in kelvin
- 323.2 K
- Steinhart–Hart A
- 0.001
- Steinhart–Hart B
- 0
- Steinhart–Hart C
- 0
3,602 Ω ≈ 122 °F (50 °C).
Assumptions
- Steinhart–Hart: 1/T = A + B ln R + C (ln R)³ with T in kelvin and R in ohms; Beta: 1/T = 1/T₀ + ln(R/R₀)/B.
- The measured resistance is the sensor alone, at negligible self-heating.
Limitations
- Sensor tolerance (often ±1 % or more at 25 °C) limits accuracy no matter which equation is used.
- The coefficients belong to one sensor curve. Using another manufacturer’s values for your sensor can be off by several degrees.
Frequently asked questions
What should a 10 kΩ thermistor read at room temperature?
About 10,000 Ω at 25 °C (77 °F) — that is what “10 kΩ” means. Colder reads higher, warmer reads lower.
Can I use another brand’s table for my sensor?
Only if it is the same curve. Two 10 kΩ sensors can differ by several degrees away from 25 °C.
Should I measure with the sensor connected?
Disconnect it from the control board first, so the board’s circuit does not change the reading.
Sources
- Calibration Equations for Thermistors (EAS 199B) — G. Recktenwald, Portland State University, Department of Mechanical Engineering (2010). Steinhart–Hart equation 1/T = c₁ + c₂ ln R + c₃ (ln R)³ with T absolute; coefficients found from measured R versus T.
- NTC Thermistors (Vishay Dale data sheets, curve tables and R–T relationship) — Vishay Dale, hosted by UC Santa Barbara Physics. Beta formula R(T) = R(T₀) exp[B(1/T − 1/T₀)] is useful only over narrow ranges; Steinhart–Hart needs three calibration points and is typically within ±0.15 °C from −50 to +150 °C; Curve 1 R/R25 = 3.266 at 0 °C, 0.3602 at 50 °C, 0.1753 at 70 °C, 0.1072 at 85 °C, 9.714 at −20 °C.
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