Hardware tool
Wire Size Calculator
Estimate copper wire gauge from current, run length, voltage, phase, and drop target.
Runs in your browserResult
- Starting copper size
- 10 AWG
- Table ampacity
- 30 A
- Estimated drop
- 3 V
- Drop percentage
- 2.5%
- Load voltage
- 117 V
This simplified copper table is not an electrical design. Temperature, terminals, insulation, bundling, conduit fill, continuous loads, motor startup, code, and aluminum conductors change sizing.
How to use this wire size calculator
- Enter the known electrical values with the correct units, then check the proposed current, voltage, resistance, or wire result.
- Review the calculated totals, units, and assumptions. Check the inputs and units before relying on the result.
- Change one input at a time to compare another case, then copy or save the result you plan to use.
About this wire size calculator
Use the Wire Size Calculator to estimate copper wire gauge from current, run length, voltage, phase, and drop target. Change the inputs to compare another result.
You can also use it to compare results after changing one input.
Example
Enter a 30-amp load, system voltage, one-way run length, phase, and voltage-drop target to estimate copper wire gauge.
Common uses
- → estimate copper wire gauge from current, run length, voltage, phase, and drop target
- → compare results after changing one input
- → save an estimate for planning or comparison