WireGaugeCalc Free calculator · NEC cited · works offline
Sizing Conductor Calculator
Sizing conductor calculator work is quick with WireGaugeCalc, since you enter the load and the tool returns a wire size.
It reads your amps, copper or aluminum, and the termination temperature column, so the AWG result lines up with NEC 310.16.
You get a size you can trust before you pull the wire.
Open the calculatorEnter any two values and read the rest.
Ohm’s law: V = I × R and P = V × I. Field aid only, verify against the current NEC and your local authority having jurisdiction.
Reading load and material into a wire size
Ampacity climbs with conductor size, so a higher load points to a larger AWG.
WireGaugeCalc compares your load against the 310.16 ampacity table for the material you pick.
Copper carries more current than aluminum at the same size, so the material changes the result.
Inputs that set the conductor size
The calculator needs a few values to size the wire:
- Load in amps for the branch circuit or feeder
- Conductor material, copper or aluminum
- Termination temperature column, 60, 75, or 90 degrees C
- The NEC 310.16 ampacity for that size and column
- The next standard AWG when the load sits between sizes
One app for every NEC calculation
WireGaugeCalc keeps the calculations you reach for most in one place:
- Voltage drop and wire sizing for any run
- Conduit fill for EMT, PVC, and RMC
- Box fill and junction box sizing
- Ampacity and temperature derating
- Motor circuit and load calculations
- Conduit bend offsets and saddles
Built for the field, works offline
The whole app runs on your phone, so it keeps working in a basement, an attic, or a job site with no signal.
There is no account to create and nothing to load. Open it, run the number, and get back to work.
- No signup and no signal needed
- Answers in a tap, not a spreadsheet
- Same tool on phone, tablet, and desktop
Every result cites the NEC article
Each answer shows the table or formula it came from, so you can check the method and learn the code as you go.
That makes the app useful on the job and during exam prep, since the reasoning is right next to the number.
Switch the code year your job runs on
Jurisdictions adopt the NEC at different times, so you can match the calculation to the code in force:
- NEC 2017, 2020, and 2023 tables
- Copper and aluminum conductors
- 60, 75, and 90 degree C terminations
- Single-phase and three-phase systems
Run the number, then get back to work
Stop flipping through a paper book or hopping between calculator sites. Enter your values, read the code-cited answer, and move on. Free to use, no signup.
Open the calculatorFrequently asked questions
Which termination temperature column should I use?
Use the column that matches your terminals, which is often 75 degrees C for larger lugs. Check the equipment listing and the current NEC, and confirm with your local authority having jurisdiction.
Why does copper give a smaller size than aluminum?
Copper has higher ampacity than aluminum at the same gauge, so a copper conductor can carry the load at a smaller AWG.
Is WireGaugeCalc free to use?
Yes. Every calculator is free to run with no signup. A paid tier adds saved projects, PDF reports, and extra code years, but the core math stays free.
Does it work without internet?
Yes. The app runs on your device, so it keeps working with no signal on a job site, in a basement, or in an attic.
Are the results code accurate?
Results follow published NEC tables and standard formulas, and each answer shows the article it came from. It is a field aid, not a stamp of approval, so verify against the current code and your local authority before you wire anything.
Which NEC code year does it use?
You can switch between NEC 2017, 2020, and 2023, since jurisdictions adopt the code at different times. Pick the year your job runs on.