WireGaugeCalc Free calculator · NEC cited · works offline
Load Calculator
Load calculator is fast with WireGaugeCalc, since you enter each load in watts or amps and the tool sums the total demand on the service.
It applies the standard demand factors from NEC Article 220, so the general lighting, appliance, and continuous loads are weighted the way an inspector expects.
You get a total amperage and a suggested service size in seconds, which makes planning a panel or upgrade straightforward.
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.
Why a Dwelling Load Calculation Matters
A correct load calculation tells you whether a 100A service is enough or whether the job needs 200A.
Since continuous loads are counted at 125 percent, the calculator separates them so the service is not undersized.
It handles general lighting at 3 VA per square foot, so the base load is figured the same way every time.
What the Service Load Calculation Covers
Enter the building loads and the calculator returns the demand:
- General lighting at 3 VA per square foot of living area
- Small appliance and laundry branch circuits at 1500 VA each
- Fixed appliances with the NEC demand factor applied
- Largest of the heating or air conditioning load
- Range and dryer loads from the Article 220 tables
- A running total in amps at 240V single phase
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 standard or optional dwelling method?
The calculator follows the standard method in NEC Article 220 by default. Always confirm which method your local authority having jurisdiction accepts against the current NEC before you submit.
How are continuous loads handled?
Continuous loads are counted at 125 percent of their value, since they run for three hours or more. The tool flags those so the service rating covers them.
Can it size the service conductors too?
It gives you the total demand in amps, and from that you pick the service size. Verify the conductor ampacity against NEC 310.16 for your wire material and termination temperature.
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.