WireGaugeCalc Free calculator · NEC cited · works offline
Honda Generator Size Calculator
Honda generator size calculator is simple with WireGaugeCalc, since the tool totals the running watts and the starting surge of the loads you plan to run.
You list each load in watts or amps, so the calculator returns the running and peak demand.
That gives you a wattage target before you match a unit to the job.
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 generator wattage estimate works
Total demand is the sum of running watts plus the largest motor surge, since motors draw extra current at startup.
The tool adds those figures so the peak number reflects the moment a compressor or pump kicks on.
Volts times amps converts any nameplate amp rating into watts for the total.
What the generator size calculator adds up
WireGaugeCalc tallies the inputs that set generator size for your loads:
- Running watts of each appliance or tool
- Starting surge of the largest motor load
- Volts and amps for nameplates listed in amps
- 120 volt versus 240 volt loads
- A headroom margin so the unit is not run at full load
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
Why does the surge wattage matter for sizing a generator?
Motors such as fridges, pumps, and air conditioners draw several times their running current for a moment at startup. The calculator adds the largest surge to the running total so the generator can carry that spike.
Should I size a generator to its full rated wattage?
Leave headroom rather than loading the unit to its full rating, since continuous operation near the limit shortens life and risks tripping. The estimate is a planning figure, so confirm conductor and connection sizing against the 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.