Lumens to Lux Calculator
Enter total lumens and area to estimate illuminance — useful for checking if current fixtures meet office lighting targets.
Calculator
Calculator
Results
Total lumens
10,000 lm
Area
20.0 m²
Estimated lux
500 lux
10,000 lm spread evenly over 20.0 m² produces about 500 lux.
How this calculator works
Lumens describe total light output from a fixture or group of fixtures. Lux describes how much of that light reaches a surface per square meter. To convert lumens to lux, divide total lumens by the area the light covers: lux = lumens ÷ area (m²). This is the inverse of the lux-to-lumens formula and helps you answer “how bright will this setup actually be?”
Use this calculator when you already know fixture lumen ratings and want to check whether they meet a lux target. For example, two 5,000-lumen panels in a 20 m² office deliver about 500 lux if light is evenly distributed — a common general office target. Real rooms rarely distribute light perfectly; ceiling height, beam angles, and wall color all affect actual lux at the desk.
This tool assumes even distribution over the entered floor area — a simplified planning estimate. For sizing a new installation from a lux target, use our Lux to Lumens Calculator or Office Lighting Calculator instead.
Example calculations
10,000 lumens over 20 m²: 10,000 ÷ 20 = 500 lux — suitable for general office work.
6,000 lumens over 20 m²: 6,000 ÷ 20 = 300 lux — may work for screen-focused tasks with supplemental desk lighting.
3,000 lumens over 4 m² desk area: 3,000 ÷ 4 = 750 lux — bright task lighting for detailed work.
Recommended lux levels
| Space | Typical lux |
|---|---|
| General office | 300–500 |
| Detailed reading / drawing | 750–1000 |
| Meeting room | 300–500 |
| Reception | 150–300 |
| Corridor | 100–200 |
This calculator provides an estimate for general planning purposes. Actual lighting performance depends on ceiling height, fixture type, room reflectance, layout, maintenance factors, and installation conditions. For commercial projects, consult a qualified lighting designer or electrician.
Frequently Asked Questions
What is the formula to convert lumens to lux?
Lux = lumens ÷ area (m²). If you know area in square feet, convert to m² first: area_m² = ft² × 0.092903.
How many lux is 10,000 lumens in a 20 m² office?
10,000 lumens over 20 m² equals 500 lux. This is a common target for general office work.
Why is actual lux lower than this calculator shows?
Real installations lose light to ceiling height, fixture beam angles, wall absorption, and dirt on lenses. This calculator assumes even distribution over the floor area — a simplified planning estimate.
Can I use this to check if my desk lamp is bright enough?
Yes, if you know the lamp lumen output and the desk area it covers. Enter lumens and desk surface area to see estimated lux. For task lighting, 300–500 lux on the work surface is typical.
What lux level is too low for office work?
Below 200 lux, most office tasks become uncomfortable without supplemental task lighting. General desk work usually targets 300–500 lux.
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