LED Wattage and Circuit Load Calculator
Know before you wire. Enter your fixtures, voltage, and breaker, and see three answers: amps on the circuit, headroom under the 80% continuous-load limit, and what the lights cost to run each year.
This calculator produces planning estimates using P = V × I × PF and the 80% continuous-load rule (per NFPA 70, NEC 210.20(A)). Three-phase results assume a balanced load. Fixture wattages are published Access Fixtures values; confirm input watts and power factor on the current spec sheet. A licensed electrician confirms breaker size, conductor ampacity, and local code requirements.
How This Calculator Works
Single-phase current equals total watts divided by voltage times power factor, and balanced three-phase current per phase equals total watts divided by 1.732 times voltage times power factor. Annual energy equals total watts times operating hours divided by 1,000, and cost equals kilowatt-hours times your utility rate.
Want the full explanation with worked examples? Read the Wattage Formula guide for LED sports lights and wall packs.