Electrical Load Calculator
Calculate your home's electrical load using the NEC standard method. Determine required service size and panel capacity.
Major Appliances
How to Use This Calculator
This calculator uses the NEC (National Electrical Code) standard method to determine your home's electrical service requirements. Accurate load calculations ensure your electrical system can safely handle all connected equipment.
- Enter your home's total living square footage.
- Check boxes for all major electric appliances you have or plan to install.
- Adjust wattage values if you know your specific appliance ratings.
- Add any additional loads not listed (pools, workshops, etc.).
- Review the recommended service size and panel capacity.
Why This Matters
Electrical service sizing affects safety, cost, and future flexibility. Undersized service causes tripped breakers, voltage drops, and fire hazards. Oversized service wastes money on installation. The NEC calculation method provides a standardized approach that meets safety codes while being economically practical.
- Determine if your current service is adequate
- Plan for new appliance additions
- Size new construction electrical systems
- Understand NEC demand factor calculations
- Avoid costly service upgrade surprises
Worked Examples
Standard Home
2,000 sq ft home with gas heat, electric dryer, central AC, and standard appliances.
All-Electric Home
2,500 sq ft home with electric heat (15kW), heat pump, electric water heater, and dryer.
Home with EV Charger
Existing 1,800 sq ft home adding a Level 2 EV charger (7.2kW).
Common Mistakes to Avoid
- Adding up all nameplate ratings - demand factors account for non-simultaneous use.
- Forgetting about heating and cooling - these are often the largest loads.
- Not planning for future loads - EV chargers, hot tubs, and additions need capacity.
- Ignoring kitchen circuits - NEC requires two 20A small appliance circuits minimum.
- Confusing VA with watts - for residential, they are treated as equivalent.