WireGaugeCalc Free calculator · NEC cited · works offline
Find Maximum Current In Wire
Find maximum current in wire is simple with WireGaugeCalc, since you enter the gauge and the conductor material.
The calculator reads the NEC ampacity table and returns the amps the wire can carry at your temperature column.
So you can confirm a conductor handles the load before you energize it.
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.
Read Ampacity From The Wire Gauge
Ampacity rises as the wire gets thicker, so a 10 AWG copper conductor carries more amps than 12 AWG.
WireGaugeCalc pulls the value from NEC 310.16 for copper or aluminum at the 60C, 75C, or 90C column.
Since terminations limit you to their rated column, the tool uses that temperature, not the highest one.
Set The Safe Current Limit
The calculator returns a maximum current using these inputs:
- Wire gauge in AWG or kcmil
- Copper or aluminum conductor
- Termination temperature, 60C, 75C, or 90C
- Ampacity value from NEC 310.16
- Derating for ambient heat or bundled conductors
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 temperature column sets the maximum current?
Use the column that matches the lowest-rated termination on the circuit, often 75C for breakers and lugs. Sizing to the 90C column is only allowed for derating, not for the final terminal load.
Does ambient heat lower the maximum current?
Yes, high ambient temperature and bundled conductors both require derating, which cuts the usable ampacity. Verify the adjusted value against the current NEC and your local authority having jurisdiction.
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.