WireGaugeCalc Free calculator · NEC cited · works offline
Square D Motor Calculator
Square D motor calculator is fast with WireGaugeCalc, which converts horsepower and voltage into full load amps using the NEC motor tables.
It then sizes the branch-circuit conductors and shows the overload range so the numbers match what you set on a Square D starter.
You get the FLA, wire size, and overload window in one place before you order the parts.
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.
Motor Full Load Amps Without The Guesswork
The app pulls full load current from NEC Table 430.250 since motor nameplate amps and table values can differ.
Branch-circuit conductors are then sized at 125% of the motor FLA per NEC 430.22, so the wire carries the running load.
Overload protection is calculated at 115% to 125% of FLA, which lines up with how you dial in a Square D thermal overload.
What The Square D Motor Calculator Returns
Enter the motor details and the app reports the values you need to spec the gear:
- Full load amps from NEC 430.248 or 430.250 by phase
- Branch-circuit conductor size at 125% of FLA
- Overload setting range of 115% to 125%
- Short-circuit protection ceiling for the breaker or fuse
- Copper or aluminum conductor choice at 75C terminations
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
Should I use nameplate amps or the NEC table value?
Use the NEC table full load current to size conductors and overload protection. Use the actual nameplate amps only when the code section calls for them, such as setting the overload relay. Confirm the latest tables in the current NEC and with your local authority having jurisdiction.
Why is the conductor sized at 125% of full load amps?
NEC 430.22 requires branch-circuit conductors for a single continuous-duty motor to be rated at not less than 125% of the motor full load current, so the wire handles sustained running heat.
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.