WireGaugeCalc Free calculator · NEC cited · works offline
Electrical Calculator
electrical calculator tools are quick with WireGaugeCalc, since the app runs wire size, voltage drop, conduit fill, and box fill from one screen.
You pick the math you need, enter the values, and the app applies the matching NEC rule and returns a clear number.
You get the working calculator embedded right here, so the on-the-job math is done before you reach for a pencil.
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.
A free electrician calculator online for daily field math
Ohm's law ties voltage, current, and resistance together, so the app solves for the value you are missing once you enter the other two.
Load and current math drives wire sizing, so the same inputs flow straight into the ampacity and voltage drop tools.
Each result names the rule it used, so you can check the number against the code.
What this electrical online calculator covers
One page handles the common jobsite calculations:
- Wire size from NEC 310.16 ampacity
- Voltage drop against the 3 percent guideline
- Conduit fill at the 40 percent limit
- Box fill volume per NEC 314.16(B)
- Ohm's law for voltage, current, and resistance
- Motor full-load amps and basic load totals
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
Is this electrician calculator online free to use?
Yes, every tool on WireGaugeCalc is free and runs in your browser with no signup. You can use it from a phone on the jobsite or a laptop at the truck.
Which calculations does the app handle?
It covers wire size, voltage drop, conduit fill, box fill, ampacity, and Ohm's law. For any sizing decision, confirm the result 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.