WireGaugeCalc Free calculator · NEC cited · works offline
Home Load Calculator
Home load calculator is quick with WireGaugeCalc, since it adds general lighting, small-appliance, and fixed loads to estimate a dwelling demand.
You enter square footage, appliance ratings, and HVAC, so the tool applies demand factors and returns a total in amps.
The result helps you check whether a service can carry the load before you commit to a panel size.
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 Dwelling Service Load Adds Up
Connected load and demand load differ, since not every circuit runs at full draw at the same time.
The calculator applies NEC demand factors to lighting and appliances, so the total reflects realistic use.
It separates heating and cooling and counts the larger one, since they rarely run together.
What Goes Into The Service Calculation
The estimate pulls from the usual dwelling loads:
- General lighting at 3 VA per square foot
- Two small-appliance circuits and one laundry circuit
- Fixed appliances like range, dryer, and water heater
- The larger of heating or air conditioning
- Demand factors applied per the NEC method you choose
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
What is the difference between connected load and demand load?
Connected load is the sum of every appliance rating, while demand load applies factors because loads do not all peak together. The service is sized from the demand load.
Do I count both heating and air conditioning?
You count only the larger of the two, since they almost never operate at the same time. Confirm the noncoincident load rule against the current NEC and your local authority having jurisdiction.
Can this size a 100A versus 200A service?
The total demand in amps tells you whether a 100A service is enough or a 200A service is needed. Use it as a planning estimate and verify the final calculation against code.
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.