Estimate recommended electrical service size from connected load, demand load, voltage, phase type, and planning target. This calculator helps estimate whether a 100A, 150A, 200A, 300A, or 400A service may fit your load.
Connected load:
The calculator adds general load, small appliance circuits, laundry circuits, major appliances, EV charger load, shop equipment, and future load reserve.
Demand load:
The connected load is multiplied by the selected demand factor to estimate service demand load.
Service size:
The demand amps are divided by the selected planning target and rounded up to a common service size.
An electrical service size calculator helps estimate whether a 100A, 150A, 200A, 300A, or 400A service may be appropriate for a home, shop, outbuilding, or small business.
It can help with service upgrade planning, EV charger planning, HVAC upgrades, large appliance additions, workshop loads, subpanel planning, additions, and general electrical planning.
Your result shows recommended service size, service size at your planning target, connected load, demand load, demand amps, existing service load percentage, remaining capacity, and comparison scenarios.
Add the electrical loads, apply appropriate demand factors, convert the demand load to amps, then choose a service size that can handle that demand load with the desired planning margin.
A 200 amp service is common for many homes, but whether it is enough depends on calculated demand load, EV chargers, HVAC, appliances, shop equipment, and future loads.
No. A subpanel can add breaker spaces and distribute circuits, but the total available power is still limited by the main electrical service size.
No. This is a simplified planning tool. Official service sizing depends on electrical code, utility requirements, equipment nameplates, demand factors, service conductors, permits, and inspection rules.