How Many Lights Do I Need? A Room-by-Room Guide

The Basic Formula

To calculate how many light fixtures you need, use this simple formula: (Room square footage x desired foot-candles) / lumens per fixture = number of fixtures. Foot-candles measure light intensity at a surface. One foot-candle equals one lumen per square foot.

Living Room (10-20 foot-candles)

Living rooms need moderate, ambient lighting. For a 250 sq ft living room at 15 foot-candles, you need 3,750 lumens. If each recessed light provides 750 lumens, you would need 5 fixtures. Supplement with floor lamps or wall sconces for layered lighting.

Kitchen (30-50 foot-candles)

Kitchens require brighter light, especially over countertops and islands. A 150 sq ft kitchen at 40 foot-candles needs 6,000 lumens. That translates to about 8 recessed lights at 750 lumens each. Add under-cabinet lighting for task areas.

Bedroom (10-20 foot-candles)

Bedrooms should feel relaxed. A 200 sq ft bedroom at 15 foot-candles needs 3,000 lumens — roughly 4 recessed lights. Pair with bedside table lamps for reading tasks.

Bathroom (30-40 foot-candles)

Bathrooms need bright, even light for grooming. A 60 sq ft bathroom at 35 foot-candles needs 2,100 lumens — about 3 recessed lights plus vanity lighting.

Home Office (40-60 foot-candles)

Proper office lighting reduces eye strain and boosts productivity. A 120 sq ft office at 50 foot-candles needs 6,000 lumens. Use 4-6 recessed lights plus a desk lamp for focused tasks.

Garage / Workshop (50-70 foot-candles)

Workshops need plenty of bright, even light. A 400 sq ft garage at 60 foot-candles needs 24,000 lumens. LED shop lights or high-bay fixtures are the most efficient solution here.

Pro Tips

• Always layer your lighting: ambient + task + accent for the best results.
• Use dimmers to adjust brightness throughout the day.
• Higher ceilings require more lumens — add 10-20% for every foot above 8 feet.
• When in doubt, plan for slightly more light than you think you need. It is easier to dim down than to add fixtures later.