Lighting Circuit Load Calculator
Use this lighting circuit load workflow for early branch-load screening when fixture watts, quantity, multiplier, voltage, phase, and comparison breaker value are known.
- Total fixture watts
- W
- Adjusted circuit load
- VA
- Circuit current
- A
- Adjusted VA per fixture
- VA
- Max fixtures by entered breaker
- fixtures
- Entered breaker margin
- A
Calculation details
- Capacity status
- Calculation basis
- Selection boundary
Recent results
Formulas
- Total fixture watts = fixture watts x fixture count
- Adjusted circuit VA = total fixture watts x continuous multiplier percent / 100
- Circuit current = adjusted circuit VA / (phase multiplier x voltage)
- Adjusted VA per fixture = fixture watts x continuous multiplier percent / 100
- Max fixtures by entered breaker = floor(entered breaker amps x voltage x phase multiplier / adjusted VA per fixture)
Use this calculator
Estimate total fixture watts, adjusted circuit VA, circuit current, adjusted VA per fixture, max fixtures by entered breaker, and breaker margin.
Read the result
Review the calculated values with their displayed units and assumptions. The result is a planning aid for the stated inputs, not a final equipment or installation decision.
Check before final work
This lighting circuit load estimate uses entered fixture and breaker values. It does not select breakers, conductors, controls, fixtures, or prove code compliance.
FAQs
Does this choose a breaker size?
No. The breaker value is only an entered comparison value.
Is this different from LED Driver Load Calculator?
Yes. This page starts from fixture watts and count. LED Driver Load starts from driver watts, power factor, and driver quantity.
Can this approve a lighting branch circuit?
No. Final circuit design needs conductor, breaker, controls, fixture, and code review.