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Help Center » Wire Resistance and Voltage Drop Calculator

Wire Resistance and Voltage Drop Calculator

First, enter the length of your cable run in either feet or meters. Second, enter the total current draw of your load. Change your source voltage if necessary (the average 12V power supply outputs 13.85 VDC). Then click on "Calculate" to display the resistance, voltage drop, output voltage and precentage loss. A recommended wire gauge is highlighted that provides less than 4% loss.

All measurements assume DC (Direct Current) voltage with stranded copper wire with a 2% lay factor.

Length of Cable (Feet)  or   (Meters)
Load Current (Amps)
Source Voltage (DC Volts)
  Calculate

  Size Diameter Resistance @ 77°F Resistance
for length
(Ohms)
Voltage
Drop
(Volts)
Output Voltage
(Source
less Drop)
Percentage Loss (%)
  AWG Metric
mm2
inch mm ohm/1000' ohm/km
  24 0.205 0.0232 0.590 26.1823 85.900
  22 0.326 0.0293 0.744 16.4592 54.000
  20 0.518 0.0369 0.938 10.3632 34.000
  18 0.823 0.0465 1.182 6.5227 21.400
  16 1.309 0.0587 1.491 4.0843 13.400
  14 2.081 0.0740 1.880 2.5756 8.450
  12 3.309 0.0933 2.371 1.6215 5.320
  10 5.261 0.1177 2.989 1.0180 3.340
  8 8.366 0.1484 3.770 0.6401 2.100
  6 13.302 0.1871 4.753 0.4023 1.320
  4 21.151 0.2360 5.994 0.2533 0.831
  2 33.631 0.2976 7.558 0.1594 0.523
  1 42.408 0.3341 8.487 0.1265 0.415
  1/0 53.475 0.3752 9.530 0.1003 0.329
  2/0 67.431 0.4213 10.702 0.0796 0.261
  3/0 85.029 0.4732 12.018 0.0631 0.207
  4/0 107.219 0.5313 13.495 0.0500 0.164

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