How to Choose an LED Power Supply

The power supply must be sized to the strip’s total load, the correct voltage, and enough headroom. If the supply is undersized, you get voltage drop, flicker, and instability. If it is sized correctly, the installation runs more reliably and lasts longer.

Quick answer

Calculate the total load of the LED strip: watt per meter × length. Then add about 20% headroom. Choose a power supply with the same voltage as the strip, 12V or 24V, and check whether you need dimming compatibility.

Simple sizing formula

Required power = watts per meter × length + 20% headroom

Example: a 14.4 W/m strip over 5 meters uses 72 W. With 20% headroom, the recommended supply is at least 86 W, so the next standard size would be 100 W.

What to check before ordering

  1. Find the strip’s watts per meter.
  2. Calculate the total load for the real length.
  3. Add headroom.
  4. Choose the correct voltage: 12V or 24V.
  5. Check whether the supply supports dimming or smart control.

12V or 24V

Criterion 12V 24V
Compatibility Only with 12V strips Only with 24V strips
Longer runs More sensitive to voltage drop Usually more stable
Recommendation Small projects Medium and longer projects

Common mistakes

  • choosing a supply without enough headroom
  • mixing 12V and 24V parts
  • ignoring voltage drop across the run
  • using a supply without enough protection

FAQ

Why do I need headroom?

Headroom reduces heat and lets the supply run more steadily instead of being pushed to the limit.

Can I use a power supply that is larger than the calculated load?

Yes, as long as the voltage matches. The key is not to undersize the supply.

What should I choose for long LED strip runs?

24V is often the safer choice for longer runs, but the supply still needs to be sized from the actual load.

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