Fit three thermistor points and derive reliable coefficients. Check Kelvin conversions and predicted temperatures instantly. Clean outputs support calibration work, testing, documentation, and sharing.
| Example Point | Resistance (Ω) | Temperature (°C) | Temperature (K) |
|---|---|---|---|
| Point 1 | 32650 | 0 | 273.15 |
| Point 2 | 10000 | 25 | 298.15 |
| Point 3 | 3550 | 50 | 323.15 |
This sample resembles a common 10k NTC thermistor set. You can replace it with your own measured values.
The Steinhart Hart model is:
1 / T = A + B ln(R) + C [ln(R)]3
T is absolute temperature in Kelvin. R is resistance in ohms. A, B, and C are coefficients found from three known calibration points.
This page solves the three simultaneous equations below:
1 / T1 = A + B ln(R1) + C [ln(R1)]3
1 / T2 = A + B ln(R2) + C [ln(R2)]3
1 / T3 = A + B ln(R3) + C [ln(R3)]3
Once the coefficients are known, the page estimates temperature from any additional resistance value.
The Steinhart Hart model is widely used with NTC thermistors. It links resistance to absolute temperature. This calculator helps you derive the A, B, and C coefficients from three calibration points. It also estimates temperature for any additional resistance value. That makes it useful for design, testing, and sensor verification.
Thermistors are not linear devices. Their resistance changes rapidly with temperature. A simple straight line gives poor results over broad ranges. The Steinhart Hart equation gives a better fit. It uses the natural logarithm of resistance and a cubic term. That structure improves accuracy across practical operating ranges.
Enter three known resistance and temperature pairs. The page converts Celsius to Kelvin when needed. It then solves a three equation system to find A, B, and C. After that, it can predict temperature from another resistance reading. A verification table is also shown. This helps you confirm the generated coefficients before using them in code or hardware work.
The coefficient block lists A, B, and C in scientific notation. The equation summary shows the fitted model. The verification section compares each calibration point with the recalculated value. With three exact points, the fit should be extremely close. Small differences may appear only from rounding. The optional target reading gives temperature in Kelvin and Celsius for quick reference.
You can use these coefficients in embedded projects, data loggers, calibration sheets, laboratory analysis, and control systems. They are useful when building temperature measurement circuits or replacing a thermistor in an existing design. Export options also make reporting easier. Save the table as CSV for spreadsheets. Save the summary as PDF for records, testing files, or client documentation.
Good calibration points improve results. Use stable measurements. Spread the three temperatures across your real working range. Keep resistance units consistent. Enter temperatures carefully. Use Kelvin only for formula work, even if you type Celsius here. If your thermistor data sheet provides more than three points, choose representative values. Then compare the predicted temperatures against published tables. That check helps you spot typing mistakes, poor point selection, or unsuitable data before deployment.
It finds the Steinhart Hart coefficients A, B, and C from three thermistor calibration points. It can also estimate temperature from an extra resistance value.
The Steinhart Hart equation uses absolute temperature. Kelvin is required because the formula works with 1 divided by temperature, and absolute scale avoids invalid results.
Yes. Select Celsius in the unit field. The page converts those values to Kelvin before solving the equations and keeps Celsius visible in the result tables.
The model has three unknown coefficients. Three calibration points provide three equations, which lets the page solve for A, B, and C directly.
The system can become singular and unsolvable. Use three distinct resistance values taken at different temperatures so the coefficient matrix remains valid.
It should match very closely because the same three points are used to fit the model. Tiny differences may appear from floating point rounding.
Use it when you already know the fitted coefficients should come from your three inputs and you want a quick temperature estimate for another measured resistance.
CSV is useful for spreadsheet work and archived datasets. PDF is useful for reports, calibration records, design reviews, and documentation handoff.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.