Interactive ToolNEC 2023 Article 220 · Updated Feb 2026

Panel Load Calculator

Can your panel handle a new load? Tell us about your home, add your existing circuits, and this calculator runs a real NEC Article 220 demand calculation to show whether you can add an EV charger, hot tub, or other load without a service upgrade.

Frequently asked questions

How do I know what size service I have?

Check the main breaker at the top of your panel. It will say 100, 125, 150, or 200 amps. If you do not have a main breaker, check the meter base or call your utility.

What happens if my panel is overloaded?

An overloaded panel can cause breakers to trip frequently, overheating of wires and connections, and potential fire hazards. If your load calculation exceeds your service size, you need a service upgrade before adding new circuits.

Do I need a permit to add a circuit?

In most jurisdictions, yes. Adding a new circuit requires a permit and inspection. Check our state-by-state permit guide for your specific requirements.

How accurate is this calculator?

This calculator uses the NEC Article 220 standard method for dwelling unit load calculations. It applies the same demand factors that electricians and inspectors use. For a complete load calculation, consult a licensed electrician who can also account for future loads and local amendments.

Requirements vary by state. NEC edition, licensing, permits, and GFCI rules differ by jurisdiction. Check your state or pick it below for personalized info across WireRef.
This calculator uses the NEC Article 220 Standard Method for dwelling unit load calculations. It provides an estimate for planning purposes. A licensed electrician should verify the calculation before any service changes. Local code amendments may affect results.