Lumens to Lux Converter
1,000 lumens spread evenly over 10 square metres gives 100 lux.
Quick answer: Divide the lumens by the area in square metres. For example, 1,000 lm over 10 square metres is 100 lux, 800 lm over 12 square metres is 66.667 lux and 3,000 lm over 25 square metres is 120 lux.
The lumens to lux formula
Illuminance in lux equals luminous flux in lumens divided by area in square metres.
Divide the lux by 10.764 to get foot-candles.
Take 1,000 lm over 10 square metres. 1,000 ÷ 10 gives 100 lux.
Take 800 lm over 12 square metres. 800 ÷ 12 gives 66.667 lux.
One lux is one lumen per square metre
One lux is the light from one lumen spread evenly over one square metre (NFSA: Lux and foot-candles). So lux is just lumens divided by area.
Lumens describe how much light a lamp gives out. Lux describes how much of it lands on a surface.
How to convert lumens to lux step by step
- Read the lamp output in lumens.
- Measure the lit area in square metres.
- Divide the lumens by the area to get lux.
- Divide by 10.764 for foot-candles.
Example 1: 1,000 lm over 10 square metres
- Start with 1,000 lm over 10 square metres.
- 1,000 ÷ 10 = 100.
- The illuminance is 100 lux.
1,000 lm over 10 square metres = 100 lux
Example 2: 800 lm over 12 square metres
- Start with 800 lm over 12 square metres.
- 800 ÷ 12 = 66.667.
- The illuminance is 66.667 lux.
800 lm over 12 square metres = 66.667 lux
Example 3: 3,000 lm over 25 square metres
- Start with 3,000 lm over 25 square metres.
- 3,000 ÷ 25 = 120.
- The illuminance is 120 lux.
3,000 lm over 25 square metres = 120 lux
The three examples below use common sizes.
Each one shows the sum in full.
lumens to lux conversion table
| Light and area | Illuminance (lux) | Illuminance (fc) |
|---|---|---|
| 100 lm over 2 square metres | 50 lux | 4.645 foot-candles |
| 200 lm over 4 square metres | 50 lux | 4.645 foot-candles |
| 450 lm over 6 square metres | 75 lux | 6.968 foot-candles |
| 800 lm over 10 square metres | 80 lux | 7.432 foot-candles |
| 800 lm over 12 square metres | 66.667 lux | 6.194 foot-candles |
| 1,000 lm over 10 square metres | 100 lux | 9.29 foot-candles |
| 1,500 lm over 15 square metres | 100 lux | 9.29 foot-candles |
| 2,000 lm over 16 square metres | 125 lux | 11.613 foot-candles |
| 3,000 lm over 25 square metres | 120 lux | 11.148 foot-candles |
| 4,000 lm over 30 square metres | 133.33 lux | 12.387 foot-candles |
| 5,000 lm over 40 square metres | 125 lux | 11.613 foot-candles |
| 10,000 lm over 50 square metres | 200 lux | 18.581 foot-candles |
The highlighted row is the default of the calculator. The last column gives foot-candles.
A quick mental shortcut for lumens to lux
Divide by 10 for a rough foot-candle value. 1,000 lm over 10 square metres is 100 lux, which is about 9 foot-candles.
The exact answer is 9.3 foot-candles.
Even light is an ideal
The formula assumes the light falls evenly over the whole area. In a real room, walls, shades and fixtures absorb some light, so a meter reads less.
Treat the answer as an upper estimate.
Lux and foot-candles
Lux is the metric unit and the foot-candle is the older US unit. One lux is 0.0929 foot-candles, and one foot-candle is 10.764 lux (NFSA: Lux and foot-candles).
Both measure light on a surface.
Lumens are not watts
Lumens measure light, not power. Two bulbs with the same lumens give the same light even if one uses fewer watts.
Use the lumens on the package for this page.
Quick conversion answers
| Conversion | Result |
|---|---|
| 800 lm over 10 square metres | 80 lux |
| 1,000 lm over 10 square metres | 100 lux |
| 3,000 lm over 25 square metres | 120 lux |
| 10,000 lm over 50 square metres | 200 lux |
Where this conversion is used
Home owners check if a bulb is bright enough for a room.
Photographers and designers plan light levels.
Common mistakes to avoid
- Using square feet. This page needs square metres. Use the foot-candle page for feet.
- Confusing lumens with watts. Lumens are light output.
- Assuming all light reaches the surface. Real rooms lose some.
- Mixing lux and lumens. One is per area and one is total.
Related converters
More lamp and room combinations
300 lm over 5 square metres is 60 lux. 600 lm over 8 square metres is 75 lux. 900 lm over 9 square metres is 100 lux.
1,200 lm over 12 square metres is 100 lux. 1,800 lm over 20 square metres is 90 lux. 2,400 lm over 18 square metres is 133.3 lux.
3,500 lm over 28 square metres is 125 lux. 6,000 lm over 45 square metres is 133.3 lux. 8,000 lm over 60 square metres is 133.3 lux.
Doubling the first number
600 lm over 5 square metres is 120 lux. 1,200 lm over 8 square metres is 150 lux. 1,800 lm over 9 square metres is 200 lux.
2,400 lm over 12 square metres is 200 lux. 3,600 lm over 20 square metres is 180 lux. 4,800 lm over 18 square metres is 266.7 lux.
7,000 lm over 28 square metres is 250 lux. 12,000 lm over 45 square metres is 266.7 lux. 16,000 lm over 60 square metres is 266.7 lux.
The same lamp over different areas
1,000 lm over 2 square metres is 500 lux. 1,000 lm over 5 square metres is 200 lux. 1,000 lm over 10 square metres is 100 lux.
1,000 lm over 20 square metres is 50 lux.
Frequently asked questions
How do I convert lumens to lux?
Divide the lumens by the lit area in square metres.
How many lux is 1,000 lumens over 10 square metres?
100 lux, or about 9.3 foot-candles.
Is a lux the same as a lumen per square metre?
Yes. One lux is one lumen per square metre.
Why does my meter read less?
Light is lost to walls and fixtures, and it is rarely even.
How do I turn lux into foot-candles?
Divide the lux by 10.764.
Can I convert lumens to lux without an area?
No. Lux needs an area, or a distance and a beam angle.
Sources
- NFSA: Lux and foot-candles (nfsa.gov.au)
