WireGaugeCalc Free calculator · NEC cited · works offline
Motor Calculator
motor calculator is simple with WireGaugeCalc, since you enter horsepower, voltage, and phase and the tool returns the motor full load amps.
From that current the calculator sizes the conductor and the overcurrent values that the motor needs.
The payoff is the motor numbers you need in one place before you wire the circuit.
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.
How The Electric Motor Calculator Reads Full Load Amps
Motor branch circuits are sized from the NEC full load current table, not the nameplate, so the electric motor calculator starts from horsepower and voltage.
Once it has the full load amps, it sizes the conductor at 125 percent for a single continuous motor so the wire carries the running load.
What The Motor Tool Calculates
WireGaugeCalc works through the motor values that the job needs:
- Full load amps from horsepower and voltage
- Single or three phase input
- Conductor size at 125 percent of FLA
- Branch circuit overcurrent protection
- Voltage and phase selection
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
Do I use the nameplate amps or the table FLA to size motor wire?
NEC 430.6 uses the table full load current values to size conductors and overcurrent, while the nameplate amps set the overload protection. The tool uses the table FLA for the wire size. Confirm the figures against the current NEC and your local authority having jurisdiction.
Why does motor wire get sized at 125 percent?
A single continuous motor circuit is sized at 125 percent of the full load current so the conductor handles the running load over time. The tool applies that factor for you.
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.