Further to popular request, we have designed a Voltage Drop Calculator for you to use in order to check your estimated Voltage Drop Rate.

Once you have entered in your details below, you will be generated a value in % and V. Please be advised of the following:

A response of between 0-4% is generally accepted as a viable Voltage Drop Rate and you are good to go.
A response rate of over 4% is generally not accepted and the details provided as likely not suitable.

It is important to note that voltage drop occurs not only along the positive cable to the load but also along the negative return cable. When you enter the cable length as the ‘one-way’ distance to the load the calculator assumes (for simplification) that the return distance is identical, giving you a total cable length that is twice that of your entered value.

In practice, your return cable length might be much shorter as it may be grounded to a nearby point on the chassis (at least in vehicles), so the remainder of the distance back to the battery negative should have an extremely low resistance relative to a cable. In this case, the actual voltage drop would probably be less than calculated, but it provides a ‘worst case’ figure to work with.

Please note: All calculations are made based on our cable specification and different manufactures or retailers specifications may differ.


Voltage Drop Calculator

Select cable cross-sectional area (mm2)
System nominal DC voltage (V)
Current draw (Amps)
One-way circuit length (m)
Estimated Percentage Voltage Drop (%)
Estimated Voltage Drop (V)


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