06 · Electrical

Powering Your LED Strips

Most LED strip failures are power failures. The arithmetic is simple and the consequences of skipping it are not.

LED strips run on low-voltage DC (12V or 24V). 24V is preferred for nearly all installations — longer runs, lower current, less voltage drop.

Sizing a driver: the 80% rule

Never load a driver above 80% of its rated wattage. A 100W driver should handle no more than 80W of strip. This keeps heat down and extends the life of the supply.

length (ft) × watts/ft = strip load
strip load ÷ 0.80 = minimum driver wattage

Voltage drop

On runs longer than ~32 ft, voltage drops along the strip and the far end dims and shifts cooler. Solve by powering from both ends, injecting power mid-run, splitting into shorter segments, or using 24V instead of 12V.

Trade tool

Power Supply Calculator

Enter your strip and length — get the minimum driver wattage, voltage-drop warnings, and matching PSUs from our catalog.

Open the calculator

See drivers & power supplies →

Questions on this topic

How do I size a power supply for an LED strip run?

Multiply the run length in feet by the strip's watts per foot, then divide by 0.80 so the supply runs at no more than 80 percent of its rating. A 20-foot run of 4.5 W/ft strip draws 90 W, which needs a 120 W supply. Running a driver at its full nameplate rating shortens its life and pushes it into audible or thermal trouble.