Electrical Cable Voltage Drop Calculator

By Rusty


For a specified electrical cable or tether, this calculator finds the voltage drop for a given current through the cable or the current through the cable required for a given voltage drop. In ROVs and subsea robotics, this is useful to calculate the power loss and voltage drop through a tether cable, but it’s also useful in all sorts of other applications!

(success) Enter the wire gauge, diameter, or circular area. (e.g. "16 AWG", "1.3 mm", "1.33 mm2", or "2580 cmil")

(success) Enter the number of conductors in parallel (default is 1).
(success) Enter the supply voltage. (e.g. "12 V")

(success) Enter the one-way cable length or distance. (e.g. "50 m", "150 ft", or "1.5 km")
(success) Enter the load current OR desired voltage drop and the other will be calculated. (e.g. "1.0 A" or "2 V")


Cable Length

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This calculator uses the js-quantities library by gentooboontoo for unit conversions.



Rusty is the founder and CEO of Blue Robotics. His background is in engineering but he likes to be involved in everything at Blue Robotics!