WireGaugeCalc Free calculator · NEC cited · works offline
NEC 220 Calculator
NEC 220 calculator is fast with WireGaugeCalc, since you enter your loads and the tool applies the demand factors to find the total.
It follows the Article 220 method for general lighting, appliances, and continuous loads.
You get a clear VA and amp total, so you can size the feeder or service with confidence.
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 NEC Article 220 Calculator Adds Loads
Article 220 sets the rules for counting general lighting at watts per square foot plus appliance and motor loads.
Demand factors reduce the total since not every load runs at full power at once.
Continuous loads are counted at 125 percent, so the service is not undersized.
What Goes Into The Load Total
The tool builds the Article 220 total from these inputs:
- General lighting by square footage
- Small-appliance and laundry circuits
- Fixed appliance VA ratings
- Largest motor load at 125 percent
- Demand factors applied to the totals
- Final VA and amps at the service voltage
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
Does the NEC 220 calculator use the standard or optional method?
It follows the standard Article 220 method with general lighting, appliance loads, and demand factors. The optional method in 220.82 can give a different total for some dwellings.
Are continuous loads counted differently in an Article 220 calculation?
Yes. Continuous loads are figured at 125 percent of the load current. Confirm which loads are continuous and the exact factors 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.