Lumens Calculator: How Many Lumens for a Room

Use this lumens calculator to work out how many lumens a room needs and how many bulbs that takes. You can also convert watts to lumens for LED and old incandescent bulbs, and convert between lumens, lux and foot-candles.

Room length

Room width

Room

Light level

foot-candles

Bulb

Value

I have

Value

I have

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Light levels are common ranges for homes. LED efficiency varies, so check the lumens on the bulb box.

How the lumens calculator works

Lumens needed = room area in sq ft × foot-candles for the room type
Bulbs = lumens needed ÷ lumens per bulb, rounded up
Old incandescent bulbs follow the common scale: 40 W = 450 lumens, 60 W = 800, 75 W = 1,100 and 100 W = 1,600
LED watts = lumens ÷ about 90 lumens per watt. CFL uses about 60 and halogen about 17.5.
Foot-candles = lumens ÷ sq ft. Lux = lumens ÷ square metres. 1 foot-candle = 10.76 lux.

Worked example

A 14 × 12 ft bedroom:

Area: 14 × 12 = 168 sq ft
Light level: 15 foot-candles, the middle of the 10 to 20 range for bedrooms
Lumens: 168 × 15 = 2,520 lumens
Bulbs: 2,520 ÷ 800 = 3.2, rounded up to 4 bulbs of 800 lumens (60 W equivalent)

The same room as a kitchen, at 35 foot-candles, needs 5,880 lumens, or 8 bulbs of 800 lumens. If 2,500 lumens shine on that 168 sq ft room (15.6 m²), that is about 160 lux or 14.9 foot-candles.

Lumens for common rooms

Room size	Bedroom or living room (15 fc)	Kitchen or dining room (35 fc)
10 × 10 ft	1,500 lumens	3,500 lumens
12 × 12 ft	2,160 lumens	5,040 lumens
14 × 12 ft	2,520 lumens	5,880 lumens
20 × 15 ft	4,500 lumens	10,500 lumens

Watts to lumens

Old incandescent bulb	Lumens	LED, about
40 W	450	5 W
60 W	800	9 W
75 W	1,100	12 W
100 W	1,600	18 W

LED efficiency varies between bulbs, so the lumens printed on the box are the number to compare.

Tips for choosing light

Shop by lumens, not watts. Watts tell you how much power a bulb uses, not how bright it is.
Layer the light. Use overhead light for the room, then add task light for reading, cooking and grooming.
Rooms with dark walls, dark floors or high ceilings need more lumens to feel equally bright.
Pick a color temperature to match the room. About 2,700 K feels warm for living spaces, and 3,000 to 4,000 K suits kitchens, bathrooms and work areas.
For can lights, the recessed lighting calculator turns these lumens into a spaced layout. The square footage calculator works out the area of an odd-shaped room.

Frequently asked questions

How do I calculate how many lumens I need for a room?

Multiply the room’s square footage by the foot-candles it needs. A 12 × 12 ft living room at 15 foot-candles needs about 2,160 lumens. A kitchen of the same size at 35 foot-candles needs about 5,040 lumens.

How do I convert watts to lumens?

For old incandescent bulbs, 60 W gives about 800 lumens and 100 W about 1,600. For LEDs, multiply the watts by about 90, so a 9 W LED gives about 800 lumens. Check the box, since LEDs differ.

How do I convert lux to lumens?

Multiply the lux by the area in square metres. 300 lux over a 168 sq ft room (15.6 m²) is about 4,680 lumens. For foot-candles, multiply by the area in square feet instead.

How many lumens per square foot do I need?

One lumen per square foot is one foot-candle. Living rooms and bedrooms need about 10 to 20, kitchens and dining rooms about 30 to 40, and bathrooms and home offices about 20 to 50.

How many lumens is a 60 watt bulb?

About 800 lumens. LED bulbs sold as “60 W equivalent” give about 800 lumens while using only around 8 to 10 W.

Results are estimates for planning. Light levels are a matter of comfort as well as numbers, so adjust to suit the room. See How We Calculate for the formulas we use.