WireGaugeCalc Free calculator · NEC cited · works offline
Electrical Code Calculator
Electrical code calculator work is simple with WireGaugeCalc, since each tool pulls from NEC tables for ampacity, conduit fill, and box volume.
You enter your conductor, load, and length, so the result reflects the code section that applies to that circuit.
That keeps your install ready for an inspection without guesswork.
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.
Calculations Tied To NEC Sections
Wire and ampacity results use NEC 310.16, so the column matches your termination temperature.
Conduit fill follows Chapter 9 and the 40% limit, since overfilling a raceway is a common red tag.
Box fill counts conductor volume under NEC 314.16(B), so crowded boxes get caught early.
Where The Code Calculator Helps On Site
Use it to check the spots inspectors look at first:
- Conductor size and 60/75/90 degree C ampacity
- Voltage drop on long branch-circuit runs
- Raceway fill for EMT, PVC, and RMC
- Box fill for devices, splices, and grounds
- Copper versus aluminum conductor differences
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 NEC tables does the calculator use?
Ampacity comes from NEC 310.16, conduit fill from Chapter 9, and box fill from 314.16(B). Each result names the value it relied on.
Can I trust the result for a permit job?
Use it as a quick check, not a stamp. Confirm every value against the current NEC edition and your local authority having jurisdiction, since amendments vary by area.
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.