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Voltage Drop Calculator

This is a calculator for the calculation how the supplied energy of a voltage source is reduced as electric current moves through an electrical circuit, based on the load current, cable distance, and cable size. Please note: this calculator assume the circuit is operate in a normal condition—room temperature with normal frequency. The actual voltage drop can vary depend on the condition of the cable, the conduit being used, the temperature, the connector, the frequency etc. And the voltage drop for industry standard is no greater than 10%.

1. Initial Voltage
DC 12V
2. Current (Amps)
3. Cable Length (ft/meter)
(ft) or (meter)
4. Cable Size (AWG)

Note: Industry standard is a voltage drop of no greater than 10%.

How to use this tool:

  • Enter the current of your camera in amps. Note: 1000mA = 1amp. Thus, if your camera draws 200mA, enter 0.2 into this field
  • Enter the cable lenghth in feet
  • Enter the size of your cable
  • Click "Calculate". OR click "Cancel" to clear the results and start again.
Example 1

For a DC 12V, a 200 mA camera at 50 feet on standard 18 awg will have a voltage drop of 0.13 volts. Industry standard is +/- 10% which is 1.2 volts In this example, you are within limits.

Example 2

DC 12V, 900 ma at a distance of 150 feet on 18 awg would give you a drop of 1.73 volts, which is greater than acceptable limits. The way to get around this is to have a shorter cable run, or increase the size of your power cable. In this example, increasing the power wire to 16 awg would decrease the voltage drop to 1.08 volts, which is within limits.