WireGaugeCalc Free calculator · NEC cited · works offline
Load Calculation For Small Apartment
Load calculation for small apartment is simple with WireGaugeCalc.
You enter the square footage, fixed appliances, and HVAC, and the tool applies the NEC Article 220 demand factors to find the total VA.
Since the demand factors reduce the raw connected load, the calculator shows a realistic service size instead of an oversized one.
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.
Applying NEC Article 220 Demand Factors
The general lighting load starts at 3 VA per square foot, so a small unit builds a modest base before appliances are added.
Small-appliance and laundry circuits add 1500 VA each, since NEC 220.52 requires them in dwelling calculations.
The first 3000 VA counts at 100%, then the remainder is reduced, so the standard method trims the total to a usable demand.
What Goes Into The Dwelling Load
A small apartment calculation pulls from these loads:
- General lighting at 3 VA per square foot.
- Two small-appliance circuits at 1500 VA each.
- One laundry circuit at 1500 VA.
- Nameplate ratings for fixed appliances like a range or water heater.
- The larger of heating or air conditioning, not both.
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 service size does a small apartment usually need?
Many small units land near a 60-amp to 100-amp service after demand factors are applied, though electric heat or a range can push it higher. Run the full calculation, since square footage and appliances vary, and verify against the current NEC and your local authority having jurisdiction.
Do I count both the heating and cooling load?
No, NEC 220.60 lets you use only the larger of the two, since they do not run at the same time. Adding both would oversize the service.
Does the range get its nameplate rating in the calculation?
Electric ranges use the demand values in NEC Table 220.55, which are lower than the full nameplate for a single unit. That demand allowance keeps the total realistic.
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.