WireGaugeCalc Free calculator · NEC cited · works offline
45 Amp Wire Gauge
45 amp wire gauge is simple with WireGaugeCalc, since you enter the load and read the conductor size that carries it.
It checks the NEC 310.16 ampacity table for copper or aluminum at your termination temperature.
So you land on a size that meets the load and the terminal rating.
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.
Size The Conductor For A 45 Amp Load
You enter 45 amps, pick copper or aluminum, and set the termination temperature, and the calculator returns the gauge.
Since the conductor must carry the full load, it reads the ampacity column that matches your terminals.
The result shows the size and its rating, so you can confirm it clears 45 amps with margin.
What Sets The Right Gauge
Three inputs decide the conductor for a 45 amp load:
- Load current of 45 amps
- Copper or aluminum conductor
- 60C, 75C, or 90C termination column
- Reads ampacity from NEC 310.16
- Returns the smallest gauge that carries the load
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
What copper wire size handles a 45 amp load?
At the 75C column, 8 AWG copper is rated 50 amps, which clears a 45 amp load. Verify the termination temperature and any adjustments against the current NEC and your local authority having jurisdiction.
Do I need to round the breaker up to 50 amps?
A 45 amp standard breaker is not common, so loads near that level often use a 50 amp overcurrent device. The wire must still be rated for the breaker after any derating.
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.