Indoor LED wall
- Load: 1,800 W
- Supply: 300 W
- Headroom: 20%
Design load is 2,160 W. At 240 W usable per supply, plan 9 supplies.
Derating often adds more supplies than a nameplate-only calculation. Always verify with the actual power supply datasheet.
LED Power Supply Calculator
Estimate how many LED power supplies are needed after derating and project headroom are applied.
Last updated:
Electrical safety disclaimer: This calculator estimates power supply count for early planning only. Breaker sizing, wire gauge, grounding, conduit, thermal design, waterproofing, and code compliance must be handled by qualified electrical engineers. Incorrect electrical design can create fire, shock, and equipment damage risks.
Power supply sizing formula
Design load = total LED load x (1 + headroom percent)
Usable supply watts = supply rating x derating factor (80%)
Supply count = ceil(design load / usable supply watts)- headroom
- Project reserve
- Allows for brightness peaks, environmental stress, and design margin. Typically 15-25%.
- derating factor
- Continuous-use reserve
- This calculator uses 80% of nameplate output as a conservative planning value. Follow manufacturer datasheets for exact derating.
Power supply examples
Outdoor cabinet run
- Load: 4,500 W
- Supply: 400 W
- Headroom: 25%
Design load is 5,625 W. At 320 W usable per supply, plan 18 supplies.
Outdoor thermal conditions usually justify conservative headroom. Consider three-phase distribution for loads above 3-4 kW.
Retail display with redundancy
- Load: 2,400 W
- Supply: 200 W
- Headroom: 20%
Design load is 2,880 W. At 160 W usable per supply, plan 18 supplies.
Critical installations may add N+1 redundancy on top of this count. Discuss redundancy requirements with the project engineer.
Common mistakes in LED power supply planning
Using nameplate output without derating
Running power supplies at 100% output continuously reduces lifespan and increases failure risk. Always apply manufacturer-recommended derating for continuous loads.
Skipping headroom for brightness peaks
LED displays often exceed average power during bright content. Without headroom, power supplies may shut down or trip protection circuits during peak scenes.
Not accounting for environmental conditions
High ambient temperature, altitude, and enclosed installations reduce power supply capacity. Outdoor and enclosed setups need additional thermal margin.
Mixing power supply models without validation
Different power supply models may have different output curves, start-up behavior, and protection thresholds. Mixing models in one installation should be validated by the engineer.
Power supply configured? Next, estimate energy consumption and running cost.
Power supply FAQ
Use this result as an estimate
Electrical calculations can create fire, shock, and equipment risks if misused. Treat this as an early estimate and verify the final design with qualified electrical and LED engineers.
Your Privacy is Protected
All calculations run locally in your browser. We do not store or transmit your data.
Related Calculators
Explore more tools in the led category