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Analogue Sensor Scaling Calculator

Work out analogue sensor scaling instantly with clear inputs, formula shown and shareable results.

About Analogue Sensor Scaling Calculator

Scaling a 4-20 mA transmitter is a linear map: fraction of span equals (reading - 4)/16, and the engineering value is the minimum plus that fraction of the range. The live-zero at 4 mA is deliberate — a broken wire reads 0 mA, which is distinguishable from a genuine zero measurement.

Formula

Linear scaling

value = min + (reading - signal min) / (signal max - signal min) x (max - min)

Worked example

With the default values below, Analogue Sensor Scaling Calculator returns Scaled engineering value of 150.00. Change any input above and every figure here is recalculated in your browser.

Inputs used

Signal at minimum
4 mA
Signal at full scale
20 mA
Engineering value at full scale
250 units
Present signal
13.6 mA

Results

Scaled engineering value
150.00 units
Signal span
16.00 mA
Percentage of span
60.00% %
Value per 0.01 mA
0.15625 units

Step by step

  1. 1Values used
  2. 2Linear scaling
  3. 3Scaled engineering value= 150.00 units
  4. 4Signal span= 16.00 mA
  5. 5Percentage of span= 60.00 %
  6. 6Value per 0.01 mA= 0.15625 units

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 5 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Why 4-20 mA and not 0-20?

The 4 mA live zero powers the transmitter and lets a broken loop be detected, since 0 mA can never be a valid reading.

Why current rather than voltage?

Current is unaffected by wiring resistance, so long cable runs cause no error, and the loop is far less susceptible to induced noise.

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