Thermocouple to Voltage Calculator

Calculator Input

Example Data Table

This example uses a Type K sensor, a 0 °C reference junction, and the linear approximation used by this calculator.

Formula Used

This calculator uses a linear engineering estimate based on the thermocouple Seebeck coefficient.

Temperature difference: ΔT = T_hot - T_ref

Voltage in microvolts: E_uV = S × ΔT

Voltage in millivolts: E_mV = (S × ΔT) / 1000

Where:

• S = approximate thermocouple sensitivity in uV/°C
• T_hot = measurement junction temperature
• T_ref = reference junction temperature

This method is useful for quick checks, planning, and approximate signal estimation. It does not replace official nonlinear reference tables.

How to Use This Calculator

1. Select the thermocouple type that matches your probe.
2. Enter the measurement junction temperature.
3. Enter the reference junction temperature.
4. Choose the temperature unit used for your entries.
5. Select the desired output voltage unit.
6. Set decimal places for the displayed result.
7. Optionally enter graph start and graph end temperatures.
8. Choose how many graph points you want plotted.
9. Click the calculate button to show the result above the form.
10. Use the CSV and PDF buttons to export the output.

Engineering Notes

Thermocouples create voltage from the temperature difference between the measurement junction and the reference junction. The selected sensor type changes the sensitivity, so the same temperature difference can produce a different voltage. This page helps with quick instrumentation checks, input scaling reviews, and maintenance documentation.

For control systems, signal conditioning, and transmitter setup, this estimate can help confirm whether the expected input is in a practical range. Use official reference tables or manufacturer data when precision matters, especially across wide temperature spans or high-accuracy calibration work.

FAQs

1) Is the voltage result exact?

No. This calculator uses a linear Seebeck approximation for quick engineering estimates. Real thermocouple outputs are nonlinear, so certified reference tables are better for precision work.

2) Why is the reference junction temperature needed?

A thermocouple responds to temperature difference, not absolute hot-junction temperature alone. The reference junction sets the second temperature that defines the generated voltage.

3) Can the calculator return a negative voltage?

Yes. If the measurement junction is colder than the reference junction, the temperature difference becomes negative, so the estimated voltage also becomes negative.

4) Which thermocouple type should I choose?

Select the exact type installed in your process or instrument. Different types use different materials, sensitivities, and working ranges, so the voltage estimate changes.

5) Why do some types produce much smaller voltages?

Each thermocouple type has its own approximate sensitivity. Noble-metal types such as R and S typically generate less voltage per degree than base-metal types.

6) What does the graph represent?

The graph plots estimated output voltage against measurement junction temperature while keeping the selected reference junction temperature fixed. It helps visualize signal trend and span.

7) Can I use the exports in reports?

Yes. The CSV file is useful for spreadsheets and logs. The PDF file is useful for report attachments, maintenance notes, and quick documentation.

8) When should I use official lookup tables instead?

Use official tables for calibration, compliance work, wide-range analysis, sensor verification, or whenever small temperature errors could affect product quality or safety.