Lumens per Square Foot by Room
Pick a room and enter its size to get the lumens per square foot from the guides, the total lumens for the room and how many bulbs of your brightness that takes.
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How to use the Lumens per Square Foot Calculator
- Choose a “Room or area”: living room, dining room, bedroom, kitchen (general light), kitchen counters and stove, bathroom, hallway, or laundry room.
- Enter the “Room length” and the “Room width”. For each one, choose the unit: ft, in, cm or m.
- Enter the “Lumens of one bulb”. The default is 800, which is only an example. Use the lumen rating printed on your bulb’s packaging.
- Open “More options” to set “Light levels from” (the guide) and “Level inside the guide’s range” (low or high end). The tool starts with the lighting-vendor table of IES levels at the low end.
- Read the results: “Light level used”, “Total lumens for the room”, “Bulbs needed”, “Same level in lux”, “Room area” and “Guide’s range for this room”.
- Check any warning. The tool warns if the lumens per bulb is under 100 or over 3,000, or if the room is under 10 square feet or over 2,000 square feet. These warnings usually mean a unit was entered by mistake. A blank, text, zero or negative entry stops the calculation, so fix the entry and try again.
The tool also shows the guide’s whole range for the room as total lumens. Change the guide or the end of the range to compare the numbers before you choose a bulb count.
How many lumens per square foot does a room need?
The tool uses a recommended light level for each room type, written in lumens per square foot. The levels come from three public guides, and they do not agree, so the tool shows each guide’s numbers separately.
For a bedroom, the guides give 10-20, 20-50 and 20 lumens per square foot. For a hallway, they give 5-10, 5-10 and 10-20. Each figure is a starting point from a guide, not a standard for your room.
What is a footcandle, and how does it relate to lux?
A footcandle is a unit used by two of the guides. One footcandle equals one lumen per square foot. One footcandle is about 10.764 lux, so the tool converts a level to lux by multiplying by 10.764. A level of 10 lumens per square foot is about 107.6 lux.
How does the tool work out the number of bulbs a room needs?
The tool uses three steps:
- Find the area by multiplying length by width, in square feet. Then multiply the area by the recommended level to get total lumens.
- Divide the total lumens by the lumens of one bulb.
- Round the result up to a whole number of bulbs.
For example, a 14 x 12 ft living room has 168 square feet. At 10 lumens per square foot, it needs 1,680 lumens. With 800-lumen bulbs, 1,680 ÷ 800 = 2.1, which rounds up to 3 bulbs. Across the guide’s range of 10 to 20 lumens per square foot, the same room needs 1,680 to 3,360 lumens.
A 12 x 10 ft kitchen at 40 lumens per square foot (the high end of the home-living guide for general kitchen light) needs 4,800 lumens. That is exactly 6 bulbs of 800 lumens. An exact division is not rounded up.
Lumens are counted for the whole room, so recessed lights, lamps and fixtures can share the total. The result is calculated from your inputs, so it changes when you change the room size or the bulb.
Why do the guides give different numbers for the same room?
Each guide sets its own levels, so the same room can get very different results. For a bathroom, the home-living guide gives 70-80 lumens per square foot, while the vendor’s table and the lamp-maker guide give 20-50. For an 8 x 5 ft bathroom, the vendor’s high end of 50 gives 2,000 lumens, or 3 bulbs of 800 lumens. The home-living guide’s 70 (its low end) gives 2,800 lumens, or 4 bulbs.
The vendor’s table gives its levels in footcandles and names the IES as the source. That attribution is the vendor’s own. The IES Lighting Handbook was not checked for this page. The lamp maker’s guide has no single dining figure, so the tool shows a dash and an error if that guide is chosen for dining.
Sources (checked 15 October 2026): glossary.ametsoc.org · en.wikipedia.org · hunker.com · superbrightleds.com · ledvance.com
Worked examples
| Input | Result |
|---|---|
| Living room, 14 ft by 12 ft, 800 lumens per bulb | 1,680 lumens, 3 bulbs |
| Kitchen (general light), 12 ft by 10 ft, 800 lumens per bulb | 4,800 lumens, 6 bulbs |
| Bedroom, 4 m by 3.5 m, 1600 lumens per bulb | 3,013.9 lumens, 2 bulbs |
| Bathroom, 8 ft by 5 ft, 800 lumens per bulb | 2,000 lumens, 3 bulbs |
| Dining room, 12 ft by 12 ft, 1100 lumens per bulb | 4,320 lumens, 4 bulbs |
Calculated by the tool above; open it with the same values to see each step.
Frequently asked questions
What does lumens per square foot mean?
It is a light level for a room. It is the total light output, in lumens, divided by the floor area in square feet. The tool multiplies this level by the room’s area to get the total lumens.
Is lumens per square foot the same as lux?
No, but they are related. One lumen per square foot equals one footcandle, and one footcandle is about 10.764 lux. The tool shows both the level and its lux value.
Why does the bulb count round up?
A fraction of a bulb cannot be installed, so the tool rounds up to the next whole bulb. An exact result, such as 6 bulbs, is not rounded up.
Does the result mean my room meets code?
No. The result is calculated from your inputs and the guide you choose. It is a starting point, not a code requirement or a standard for your room.
Can I mix recessed lights, lamps and fixtures?
Yes. The total lumens are for the whole room, so the lights you use can be recessed lights, lamps, fixtures, or a mix. Add up the lumens of all the bulbs you plan to use.
Why does the tool show a warning?
A warning appears when a value is unusual. Lumens per bulb under 100 or over 3,000, or a room under 10 square feet or over 2,000 square feet, often means a unit was entered by mistake. Check the entry before you use the result.
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