Will your panel handle it?
Three free tools for the electrical backbone of your home: size your service, size a circuit's breaker and wire, and find the incentives that cut the cost.
Service load calculator
Estimate your total electrical demand and the service size your home needs.
Breaker & wire size
Get the breaker, conductor and ground size for a circuit from its load.
Incentive finder
See which incentives typically apply and jump to the official, always-current databases.
Common questions
How do I know what size electrical service I need?
Add your general lighting load (about 3 VA per square foot) to the nameplate ratings of major appliances, then apply NEC demand factors. The load calculator above does this with the 220.82 optional method and recommends a standard service size such as 100, 150 or 200 amps.
What size wire do I need for a given breaker?
Size the conductor so its ampacity meets or exceeds the breaker rating, using the NEC 310.16 table for your conductor material and temperature rating. For example, a 50 amp circuit on 75°C copper typically uses 6 AWG. The wire calculator gives copper and aluminum sizes plus the ground.
What is the 80 percent rule?
A continuous load — one expected to run for three hours or more, like an EV charger — must not exceed 80 percent of the breaker rating. In practice you size the breaker and wire to at least 125 percent of the continuous load, which the tools do automatically.
Do I always need a panel upgrade to add an EV or heat pump?
Often no. Many homes have enough headroom, and load-management devices can let you add a large load without upgrading. Run the readiness check on the homepage and the load calculator here to see where you stand before assuming an upgrade is required.