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How to Convert mA to Voltage


December 19, 2012

Amps Ohms Volts Gauge

Converting mA to voltage is common in HVAC when working with pressure transducers. Terminology to keep in mind includes:

  • 1 mA = 0.001 AMP (short for amperes)
  • Amps are referred to as CURRENT
  • Resistor values are in OHMS (Ω is the symbol for ohms)
  • VOLTAGE is the result of passing amps through a resistor

 

 In order to change mA (current) to voltage, you need to pass the current through a resistor.

The formula for voltage is:

E = IR
E stands for volts, I stands for amps, and R stands for resistance

 

In control circuits, the most common resistor values are 250Ω & 500Ω, although any value can be used depending upon the device.

If your control circuit is using a 250Ω resistor:
mA Amps x Resistance Volts
4 0.004 x 250Ω 1
5 0.005 x 250Ω 1.25
6 0.006 x 250Ω 1.5
7 0.007 x 250Ω 1.75
8 0.008 x 250Ω 2.0
9 0.009 x 250Ω 2.25
10 0.010 x 250Ω 2.5
11 0.011 x 250Ω 2.75
12 0.012 x 250Ω 3.0
13 0.013 x 250Ω 3.25
14 0.014 x 250Ω 3.5
15 0.015 x 250Ω 3.75
16 0.016 x 250Ω 4
17 0.017 x 250Ω 4.25
18 0.018 X 250Ω 4.5
19 0.019 x 250Ω 4.75
20 0.020 x 250Ω 5
 
If your control circuit is using a 500Ω resistor:
mA Amps x Resistance Volts
4 0.004 x 500Ω 2
5 0.005 x 500Ω 2.5
6 0.006 x 500Ω 3
7 0.007 x 500Ω 3.5
8 0.008 x 500Ω 4
9 0.009 x 500Ω 4.5
10 0.010 x 500Ω 5
11 0.011 x 500Ω 5.5
12 0.012 x 500Ω 6
13 0.013 x 500Ω 6.5
14 0.014 x 500Ω 7
15 0.015 x 500Ω 7.5
16 0.016 x 500Ω 8
17 0.017 x 500Ω 8.5
18 0.018 x 500Ω 9
19 0.019 X 500Ω 9.5
20 0.020 x 500Ω 10

 

Need help converting something else?  Visit our metric conversion chart

Topics: General Industrial OEM, Critical Environments, Process/Mfg Tank Level, HVAC/R OEM, Water and Wastewater, Industrial Vacuum, Test and Measurement, Building Automation, Barometric, Medical, OHV, Calibration, General Industrial, Alternative Fuels, Oil and Gas, Scales, HVAC/R, Semiconductor Manufacturing