What amp service do I need?
NEC Article 220.83 dwelling load calculation — check off your real loads and see whether your existing panel can fit a new EV charger or heat pump, or if you need an upgrade.
Appliances & loads
Check everything you have or plan to add:
EV charger
How this is calculated
Following NEC 220.83 (existing dwelling method): we sum general lighting at 3 VA per sq ft, two small-appliance circuits at 1,500 VA each, then add every electrical load you check. The largest motor (usually your AC compressor) gets a 25% surcharge per NEC 430.24.
We apply the standard dwelling demand factor: first 10 kVA at 100%, the remainder at 40%. Then we divide by 240V to get amperage, add 25% headroom for safe continuous operation, and round up to the next standard service size (100A, 125A, 150A, 200A, 320A, 400A). See our main panel and amperage glossary entries for more.