4-20 mA signal scaling calculator
A sensor transmits its measured value as a linear 4–20 mA current: 4 mA is the low end of the range, 20 mA the high end. Set the range and convert current to value and back.
Measurement and signal range
Current → value
Measured valueEngineering (physical) units — what the sensor actually measures: °C, bar, m³/h, and so on. The calculator converts signal current into this value.
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Percent of rangePercent of range — where the signal sits between the low and high ends: 4 mA = 0%, 12 mA = 50%, 20 mA = 100%.
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%
Value → current
Signal current
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мА
How it's calculated
- A sensor transmits its value linearly: 4 mA corresponds to the low end of the range, 20 mA to the high end.
- To convert current to value, find the signal's fraction within the 4–20 mA range and take the same fraction of the measurement range.
- The reverse conversion is the same operation in the other direction; the calculator computes both directions at once from one range.
Example: A 0–100 sensor at 12 mA: that's exactly the midpoint of the 4–20 mA range, so 50% of the scale and a value of 50.
Linear scaling: value = Hlo + (I − Ilo)/(Ihi − Ilo)·(Hhi − Hlo). Signal standard — GOST 26.011, 4–20 mA range.
This is an estimate
Verify final values against current standards, the project design, and equipment nameplates.