WireGaugeCalc Free calculator · NEC cited · works offline
Wire Gauge Calculator
wire gauge calculator work is quick with WireGaugeCalc, since you enter the load and it returns a conductor size from the NEC ampacity tables.
The tool reads NEC 310.16 and the termination temperature column you select, so the result matches how the breaker and lug are rated.
You see the smallest conductor that carries the load safely before you pull any wire.
Open the calculatorSmallest conductor whose ampacity meets the load, NEC Table 310.16. Field aid only, verify against the current NEC and your local authority having jurisdiction.
How This Electrical Wire Size Calculator Picks a Conductor
Ampacity depends on conductor material, so copper and aluminum return different gauges for the same load.
The tool follows the 60, 75, or 90 degree C column you choose, since the lowest-rated termination sets the limit.
As the load climbs, the result steps up to the next standard size from Table 310.16.
What the Wire Size Calculator Accounts For
Enter the run details and the wire conductor size calculator covers the inputs that drive the answer:
- Copper or aluminum conductors
- 60, 75, and 90 degree C termination columns
- Load in amps from the circuit
- Standard AWG and kcmil sizes
- NEC 310.16 base ampacity values
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
Should I size wire to the 75 degree C column?
For most equipment rated 100 amps or less, NEC 110.14(C) directs you to the 60 or 75 degree C column even if the conductor is rated 90 degrees. Use the lower termination rating and confirm the listing on the device. Verify against the current NEC and your local authority having jurisdiction.
Why does aluminum need a larger gauge than copper?
Aluminum has lower ampacity per size, so it carries less current than copper of the same gauge. The calculator steps aluminum up to the size that matches your load.
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.