WireGaugeCalc Free calculator · NEC cited · works offline
Online Load Calculater
Online load calculater is fast with WireGaugeCalc, which adds your general lighting, small-appliance, and fixed loads, then applies the NEC demand factors to give a total in volt-amperes and amperes.
You enter the square footage and each appliance rating, so the calculator returns the calculated service size right away.
That total tells you whether a 100, 150, or 200 amp service fits the dwelling.
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.
A House Electricity Load Calculator That Follows the Standard Method
The tool starts at 3 VA per square foot for general lighting since that is the NEC baseline for dwellings.
It then adds the two required small-appliance circuits and the laundry circuit before applying the 35% demand factor on the load above the first 10 kVA.
Large appliances like ranges and dryers are added with their own demand rules so the final number reflects the real diversified load.
What This Load Calculator Online Covers
Enter each part of the dwelling load and the calculator handles the demand math:
- General lighting at 3 VA per square foot
- Two small-appliance circuits plus the laundry circuit at 1,500 VA each
- Range, dryer, water heater, and HVAC nameplate ratings
- The 35% demand factor above the first 10 kVA
- A final total in volt-amperes and service amps at 240V
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 this use the NEC standard method or the optional method?
It uses the standard method with the tiered demand factors, which is the most common approach for new dwelling services. Confirm your result against the current NEC and your local authority having jurisdiction before you size the service.
Why is the calculated load lower than the sum of all appliances?
The NEC allows demand factors because not every load runs at once, so the 35% factor above the first 10 kVA reduces the total. This diversified number is what you use to size the service.
Will this tell me if a 200 amp service is enough?
Yes, the result is shown in service amps at 240V so you can compare it directly to 100, 150, or 200 amps. If the calculated load is close to a rating, step up to the next size.
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.