LED Strip & Power Supply Sizer

This LED strip power supply sizer helps you match 12 V or 24 V strips to a right-sized PSU and wiring plan. Enter the strip’s watts per meter (or per foot) and your total run length; the tool outputs total watts, current draw in amps, a recommended PSU wattage with headroom, and when to inject power to avoid dim ends. It also estimates a practical wire gauge and gives a short wiring checklist. Use it for single-color and tunable-white constant-voltage strips, accent lighting, shelves, coves, under-cabinet runs, and display cases.

For even brightness, keep each feed segment within a sensible maximum. As a rule of thumb, many 12 V strips are happiest with about 5 m per feed and many 24 V strips with about 10 m per feed. Higher-power strips (big watts per meter) need shorter segments; lower-power accent strips can stretch longer. The calculator adjusts the suggested max run based on your entered power density, then tells you if power injection from both ends or from the middle will help.

Pick a PSU with overhead so it runs cool and lasts longer. A 20–30% margin above calculated load is typical for LED lighting. Place the supply in a ventilated spot, respect the low-voltage polarity, and use appropriately sized copper cable. Long cable runs cause voltage drop; thicker wire reduces that drop. Keep splices tidy with screw terminals or solder plus heat-shrink, and add fusing on long or multi-run installs for safety. If you are dimming, choose a dimmable or PWM-compatible power supply designed for LED strips.

Total watts equals power density times length. Current draw is watts divided by the strip voltage (12 V or 24 V). Recommended PSU wattage applies your chosen headroom on top of the calculated watts and rounds up to a practical number. For maximum run per feed, the tool scales a baseline of about 5 m at 12 V and 10 m at 24 V for a 14.4 W/m strip; higher or lower power densities shorten or lengthen that suggestion within sensible limits. If your total exceeds the max per feed, the planner proposes splitting into parallel runs or injecting power from both ends.

Wire gauge suggestions are based on estimated current and a moderate wiring distance, targeting low voltage drop. As a simple field guide: up to ~2 A ≈ 20 AWG, up to ~5 A ≈ 18 AWG, up to ~8 A ≈ 16 AWG, up to ~12 A ≈ 14 AWG, up to ~20 A ≈ 12 AWG. Longer one-way wire lengths push you toward thicker wire. Always check your local codes and follow the power supply and strip manufacturer recommendations.