Calculator Inputs
Formula Used
Thermocouples generate a small voltage relative to a reference junction. This page converts measured millivolts into temperature by adding cold junction compensation and then interpolating within the selected thermocouple reference table.
The interpolation step uses the two nearest reference points around your input. This approach is practical for engineering workflows, trending, bench checks, maintenance work, and process review.
How to Use This Calculator
- Select the thermocouple type installed in your system.
- Enter the measured sensor voltage in millivolts.
- Enter the cold junction temperature in degrees Celsius.
- Choose your preferred output unit.
- Add any known calibration offset in degrees Celsius.
- Pick the number of decimal places for display.
- Press the convert button to view the result.
- Use the export buttons to save summary data.
Example Data Table
These sample rows show typical Type K reference values with zero cold junction correction.
| Example | Type | Measured Voltage (mV) | Cold Junction (°C) | Referenced Voltage (mV) | Approx. Temperature (°C) |
|---|---|---|---|---|---|
| 1 | K | 0.000 | 0 | 0.000 | 0 |
| 2 | K | 4.095 | 0 | 4.095 | 100 |
| 3 | K | 12.209 | 0 | 12.209 | 300 |
| 4 | K | 20.644 | 0 | 20.644 | 500 |
| 5 | K | 33.275 | 0 | 33.275 | 800 |
Frequently Asked Questions
1) Why is cold junction compensation necessary?
A thermocouple measures temperature difference, not absolute temperature. The cold junction creates part of the circuit voltage. Compensation adds its equivalent voltage before converting to the hot junction temperature.
2) What does the measured voltage represent?
It is the thermoelectric output from the installed sensor pair. The value is usually in millivolts and depends on both thermocouple type and temperature difference across the junctions.
3) Why can two thermocouple types give different temperatures?
Each thermocouple type has its own voltage-temperature curve. A Type K signal does not match a Type J or Type T curve, so selecting the correct type is essential.
4) Is this calculator suitable for calibration certificates?
It is useful for engineering estimates and practical checks. For official calibration records, use your approved standards, certified reference tables, documented uncertainty limits, and controlled procedures.
5) What does the calibration offset field do?
It shifts the calculated hot junction result by a known correction value. This is handy when you have a documented instrument bias or a verified field adjustment.
6) Why does the page show local sensitivity?
Local sensitivity estimates how many microvolts change per degree Celsius near the result point. It helps you judge responsiveness, resolution, and expected reading movement during troubleshooting.
7) Can I use negative voltages?
Yes, if the selected thermocouple type supports the corresponding subzero range. The calculator checks the reference range and warns you when the voltage falls outside supported data.
8) How are the exports generated?
The CSV export saves a structured summary row set. The PDF export creates a compact calculation report with the main inputs, intermediate values, and final temperature result.