LED Strip Power Supply Calculator

About this calculator

This calculator sizes an LED strip's power supply from the strip's length and its rated power draw per meter: total load = length × W/m, and current = watts / supply voltage (typically 12V or 24V). To keep the supply from running at its thermal limit continuously, the calculator adds headroom — commonly 20–25% above the calculated load — the same margin electricians build in for any continuous-duty circuit, since running a supply at 100% of rated capacity shortens its lifespan and risks overheating.

DIY installers wiring under-cabinet kitchen lighting, cove lighting, or accent strips use this to avoid undersized transformers that dim, flicker, or fail early, and it also flags when a run is too long for a single supply and needs to be split or fed from both ends to avoid voltage drop along the strip.