Room Lighting Calculator
Calculate recommended lumens and bulb count for any room from square footage and room type.
Covers living rooms, kitchens, bedrooms, bathrooms, and offices.
Lumens measure the total amount of visible light emitted by a source. Unlike watts (which measure energy consumption), lumens measure actual brightness. Choosing the right lumen output for a room prevents both under-lit dim spaces and harsh, eye-straining over-lit ones.
The formula: Required Lumens = Room Area (sq ft) × Foot-Candles Needed
Foot-candle requirements by room type:
- Living room (ambient): 10–20 foot-candles
- Kitchen (general): 30–40 foot-candles
- Kitchen (task areas — countertops): 70–80 foot-candles
- Bathroom (general): 70–80 foot-candles
- Bedroom: 10–20 foot-candles
- Home office: 50–70 foot-candles
- Hallway: 5–10 foot-candles
- Garage/workshop: 50–75 foot-candles
Worked example: Kitchen measuring 12 ft × 14 ft = 168 sq ft, needing 40 foot-candles for general lighting: Required lumens = 168 × 40 = 6,720 lumens
A standard 60W equivalent LED bulb produces ~800 lumens. Number of bulbs needed = 6,720 / 800 = 8.4 → use 9 bulbs (or fewer, higher-output fixtures)
Metric equivalent: 1 foot-candle = 1 lux × 0.0929 (multiply lux by 0.0929 for sq ft calculation, or use sq meters directly with lux values)
Bulb reference (LED equivalents):
- 40W equivalent: ~450 lumens
- 60W equivalent: ~800 lumens
- 75W equivalent: ~1,100 lumens
- 100W equivalent: ~1,600 lumens
Layer your lighting: General (ambient) + Task (counters, desks) + Accent (art, shelves) — each layer uses only 30–50% of the ambient level.