LED Strip Length and Power Calculator
Calculate total LED strip length needed for a room and the power supply wattage required.
Plan your LED lighting installation.
LED Strip Length and Power calculations help you plan an LED lighting installation by determining how much strip you need and what power supply to buy.
Measuring strip length: The total length depends on where you install the strips.
- Under cabinet lighting: measure the length of each cabinet section
- Cove lighting (ceiling perimeter): measure the room perimeter where strips will be mounted
- Accent lighting: measure each segment individually
For room perimeter calculations:
Perimeter = 2 × (Length + Width)
Subtract any gaps (doorways, windows, etc.) from the total.
Power consumption by strip type:
- Standard density (30 LEDs/meter): 4-7 watts per meter (1.2-2.1 watts per foot)
- High density (60 LEDs/meter): 7-14 watts per meter (2.1-4.3 watts per foot)
- Ultra-high density (120 LEDs/meter): 14-24 watts per meter (4.3-7.3 watts per foot)
- RGBW strips: typically 14-20 watts per meter (4.3-6.1 watts per foot)
Power supply sizing:
Required Wattage = Total Strip Length × Watts per Meter
Always add a 20% safety margin to avoid overloading the power supply.
Power Supply = Required Wattage × 1.2
Running a power supply at 100% capacity reduces its lifespan and can cause overheating.
Voltage considerations:
- 12V strips: maximum run length of about 5 meters (16 feet) before voltage drop causes dimming
- 24V strips: can run up to 10 meters (33 feet) before significant voltage drop
- For longer runs, inject power from both ends or use multiple power supplies
Brightness reference: A standard 60W incandescent bulb produces about 800 lumens. High-quality LED strips produce 300-1000 lumens per meter, depending on the type and density.