Service Load Calculator

Estimate electrical service load, connected load, demand load, demand amps, recommended service size, remaining capacity, and service load percentage for residential or light commercial planning.

Calculate Service Load

Service load percent = demand amps ÷ existing service amps × 100.
Your result will appear here.

How the service load calculator works

Connected load:
The calculator adds general load, small appliance circuits, laundry circuits, and fixed equipment loads.

Demand load:
The connected load is multiplied by the selected demand factor to estimate the service demand load.

Service size:
Demand amps are compared to the existing service size and rounded to a common recommended service size.

Why use a service load calculator?

A service load calculator helps estimate whether an existing electrical service may have enough capacity for current or planned loads.

It can help with service upgrade planning, EV charger planning, HVAC upgrades, large appliance additions, workshop circuits, garage panels, subpanels, additions, and general electrical planning.

What your result means

Your result shows connected watts, demand watts, demand amps, service load percentage, existing service size, remaining capacity, recommended service size, target service size, and comparison scenarios.

Service load calculator formulas

Frequently asked questions

How do I calculate electrical service load?

Add the connected electrical loads, apply appropriate demand factors, convert the demand load to amps, then compare the result to the service size.

Is service load the same as panel load?

They are related, but not always the same. Service load looks at the electrical service capacity, while panel load may focus on one panel or subpanel.

Does adding a subpanel increase service capacity?

No. A subpanel can add breaker spaces and distribution, but the available capacity is still limited by the main electrical service and calculated demand load.

Can this replace an official service load calculation?

No. This is a simplified planning tool. Official service calculations depend on electrical code, utility requirements, equipment nameplates, demand factors, service conductors, permits, and local inspection rules.