Voltage Drop Calculator
Calculate voltage drop over a wire run, to size cables correctly.
Inputs explained
- Voltage (V) — The system voltage. Example: 120.
- Current (amps) — The current the wire carries. Example: 15.
- Wire Length (feet) — One-way distance of the cable run, in feet. Example: 100.
- Wire Gauge — The wire thickness (AWG) — smaller numbers are thicker wires.
How to use it
- Fill in the fields above — each input has a hint describing exactly what to enter
- Press Calculate to get your result instantly, right on this page
- Copy the result, save the tool to favorites, or share and embed it anywhere
Understanding the result
Example: 15 A over 100 ft of 12 AWG drops a few volts — within the usual 3% limit at 120 V.
Frequently asked questions
Is the Voltage Drop Calculator free to use? Yes — it is completely free, with no sign-up, no download and no usage limits. You can use it as often as you need.
Is my data private? Yes. The calculation runs entirely in your browser — the values you enter are never sent to our servers, stored or shared with anyone.
What information do I need? Just the following: Voltage (V), Current (amps), Wire Length (feet), Wire Gauge. Each field includes a hint explaining exactly what to enter.
Can I use it on my phone? Yes — the tool is fully responsive and works on any device, and the same calculator is available in the EasyWorkCalcs mobile app.
Privacy
Everything you enter into the Voltage Drop Calculator is processed entirely in your browser. Nothing is uploaded, stored or shared — your data stays on your device.