Useful Tools / 4–20 mA Calculator

4–20 mA Calculator

Convert a linear current signal into any engineering measurement, or calculate the output signal for a known value. Choose the transmitter output range (including 0–20 mA) and configure your lower and upper engineering range values.

Configure the transmitter range

Select an output signal standard or set your own output start and end. Both conversion directions follow the selected range.

Output signal range

Output limits are always editable. Changing them switches the selector to Custom.

Output lower limit (mA)

Output upper limit (mA)

Conversion direction

Engineering lower limit

Engineering upper limit

Engineering unit

Measured current (mA)

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Signal result

The configured analog measurement span is 4 to 20 mA.

Calculated engineering value—

Output current—

Percent of span—

Signal equation—

Waiting for values

Enter settings and calculate.

Use the Output lower/upper limits in mA to match the actual sensor or transmitter: 4–20 mA, 0–20 mA or a verified custom span. Signal values outside the range are extrapolated; device-specific fault current conventions still apply.

How the calculation works

For any lower range value (LRV) and upper range value (URV), span fraction = (measured mA − selected output start) ÷ (selected output end − selected output start). The engineering value is LRV + span fraction × (URV − LRV). In the reverse direction, the expected output is output start + (engineering value − LRV) ÷ (URV − LRV) × (output end − output start).

Example: For a transmitter scaled from 0 to 100 °C, 12 mA corresponds to 50 °C, which is 50% of configured span. A negative or over-range percentage is an extrapolation, not an instrument fault code or a reliably measured value.

Educational calculation only. Confirm instrument scaling, calibration, signal fault limits and any safety-critical control settings with the device documentation.