Wire Gauge Calculator
Cable size for current, length and voltage drop.
Enter your values
Results update instantly as you type — no submit needed.
Results
- Recommended gauge
- 10 AWG
- Actual voltage drop
- 3.28 V (2.73%)
- Maximum allowed drop
- 3.6 V
- Power lost in the cable
- 65.6 W
- Note
- Always confirm against local electrical code ampacity tables.
Quick answer
Choose a wire gauge whose resistance keeps voltage drop under 3% for the current and one-way run length.
Vdrop = 2 × I × L × R_per_metre
How to use the Wire Gauge Calculator
- 1Enter the load current in amps.
- 2Enter the one-way cable run length.
- 3Set the acceptable voltage drop, usually 3%.
Frequently asked questions
Why 3% voltage drop?
It's the widely used design limit for branch circuits; more than that wastes energy and dims or overheats loads.
Does length really matter?
Yes — drop is proportional to run length, so long runs often need a gauge or two thicker than ampacity alone suggests.