Dimmer Load Calculator

Verify dimmer compatibility by comparing the total fixture load against the dimmer rated capacity.

Total Load
— watts
Versus dimmer capacity.

Usage Tip

LED fixtures draw far less than their old incandescent equivalents, but use a dimmer rated specifically for LED loads.

THE MATH
total load = fixtures × watts per fixture
safe limit = dimmer rating × 0.80
A dimmer should run at no more than 80 percent of its rated wattage to stay cool and last. The total load is the fixture count times the watts each.
Enter the number of fixtures, the watts per fixture, and the dimmer rating.
A green result means the load is within the safe limit; red means it is over.
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The calculators and tools on Formula Factory are provided for general guidance and informational purposes only. Results are estimates based on standard formulas and the values you enter — they do not constitute professional engineering, electrical, or architectural advice. Always verify calculations with a qualified professional before making decisions for any safety-critical, code-compliance, or commercial application. Formula Factory makes no representations or warranties as to the accuracy or completeness of any result, and accepts no liability for errors, omissions, or any outcomes arising from reliance on this information.