WireGaugeCalc Free calculator · NEC cited · works offline
Electrical Needs Calculation
Electrical needs calculation is quick with WireGaugeCalc, since you enter the load in amps or watts and the tool returns the conductor size and voltage drop.
It works from the demand on the circuit, so the wire and breaker match the actual draw.
That lets you plan a circuit before you cut a single foot of cable.
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.
Sizing Wire To The Actual Load
Conductor size follows the load and termination temperature, so an undersized wire gets flagged before install.
Voltage drop is checked against the 3% branch-circuit guideline, since long runs lose voltage and stress equipment.
Copper and aluminum give different results, so you pick the conductor that fits the budget and the breaker.
Inputs For A Solid Load Calculation
Give the tool a few facts and it does the rest:
- Continuous and non-continuous load in amps or watts
- Voltage and single or three phase
- One-way run length for voltage drop
- Copper or aluminum conductor
- Termination temperature rating of the device
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
How do I figure the load before sizing wire?
Add the continuous load at 125% plus the non-continuous load to set the minimum circuit demand. The calculator then sizes the conductor to carry that total.
Does the calculation account for voltage drop on long runs?
Yes, it checks the run against the 3% guideline and bumps the conductor if needed. Still verify the final size 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.