Recessed Lighting Calculator
Calculate the number of recessed lights needed for a room based on room dimensions, desired foot-candles, and light specifications.
Published by:
isCalculator Editorial Team
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How to use this tool?
Step 1: Enter the Room Length and Room Width in feet (imperial). These must be positive numbers.
Step 2: Select your Desired Foot-candles from the dropdown. Choose based on the room’s purpose (e.g., 20 for normal ambient, 50 for task lighting).
Step 3: Input the Lumen Output per Light (e.g., 800 lm for a typical LED bulb).
Step 4: Enter the Beam Angle in degrees (e.g., 60° for a standard recessed light). The angle affects how much light spreads.
Step 5: Click "Calculate Lights Needed". The result shows the recommended number of lights and a breakdown of the calculation.
- Room Area = length × width (sq ft)
- Total Lumens Needed = foot-candles × area
- Beam Angle Factor = angle ÷ 360 (adjusts for light spread)
- Effective Lumens per Light = lumen output × beam factor
- Number of Lights = total lumens needed ÷ effective lumens (rounded up)
Tip: All inputs must be positive. Use imperial units (feet) only.
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Frequently Asked Questions
Foot-candles measure brightness. For ambient lighting, 20-30 fc is typical. For task areas like kitchens, aim for 50 fc. Use lower values for bedrooms (10-20 fc).
Beam angle affects light spread. Narrow angles (25-40°) focus light, while wide angles (60-120°) spread it. The calculator uses beam angle to adjust effective lumens.
Yes, this calculator works for any recessed light type. Just input the lumen output per light (typically 600-1500 lm for LEDs).
We round up to ensure you have enough light. You can always dim lights or use fewer if you prefer slightly dimmer conditions.