Voltage Drop Calculator
On long cable runs the wire itself steals some of your voltage, and too much drop means dim lights, sluggish motors or resets. This calculator estimates that loss. It takes the one way run length, the load current, the wire cross section and the conductor material, then computes the resistance of the round trip and multiplies by the current to give the voltage dropped in the cable. The result is shown as volts lost, the voltage that actually reaches the load, and the drop as a percentage of your supply, since a common rule of thumb keeps the drop under three percent for a healthy circuit. Choose copper or aluminium and enter your numbers to size a cable properly for a solar run, a battery lead, low voltage lighting, or an audio feed. Everything runs locally in your browser, so it is instant and private.
How to use Voltage Drop Calculator
- Enter the one-way run length of the cable.
- Enter the load current in amps.
- Enter the wire cross section or gauge and pick the material.
- Read the voltage lost and the percentage drop over the run.
Frequently asked questions
How is voltage drop over a cable calculated?
It finds the conductor resistance from length, area and material, then multiplies by the current, so the drop equals current times the round-trip wire resistance.
What is the percentage drop figure?
It divides the volts lost in the cable by the source voltage to show the percentage drop, which helps you keep within a common 3 percent guideline.
Does the tool account for the return conductor?
Yes, current flows out and back, so it uses the round-trip length of the run when computing the total voltage lost.
What is Voltage Drop Calculator?
On long cable runs the wire itself steals some of your voltage, and too much drop means dim lights, sluggish motors or resets. This calculator estimates that loss.
Is Voltage Drop Calculator free to use?
Yes. Voltage Drop Calculator is completely free, with no sign-up and no usage limits.
Does Voltage Drop Calculator work in a web browser?
Yes. Voltage Drop Calculator runs in any modern web browser. There is nothing to download or install.
Is my data private with Voltage Drop Calculator?
Yes. Voltage Drop Calculator runs entirely on your device in your browser, so nothing you enter is uploaded to a server.
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Link this tool from a README, doc or site. The badge links back to this page.
[](https://yourhack.ai/voltage-drop-calculator)