Lux Calculator
Calculate illuminance in lux using lumens and room dimensions in feet.
Why Use Feet Instead of Meters?
Many homeowners and professionals in the United States use feet to measure room dimensions. While lux is a metric measurement (lumens per square meter), converting from square feet is simple. Our calculator automatically converts your input to square meters so you can get an accurate lux reading.
Formula for Lux
Lux = Lumens ÷ (Area in sq ft × 0.092903)
This ensures your lux value is accurate regardless of using feet for measurements.
Example Calculation
Suppose you have a 12 ft × 15 ft living room with 5000 total lumens:
Area (sq ft) = 12 × 15 = 180 sq ft
Area (sq m) = 180 × 0.092903 ≈ 16.72 m²
Lux = 5000 ÷ 16.72 ≈ 299 lx
This falls within the recommended 100–300 lux range for a living room.
Recommended Lux Levels
| Room Type | Recommended Lux |
|---|---|
| Living Room | 100–300 lx |
| Kitchen (General) | 300–500 lx |
| Kitchen (Task Areas) | 500–750 lx |
| Bedroom | 100–200 lx |
| Bathroom | 200–400 lx |
| Office | 300–500 lx |
| Reading Area | 500–700 lx |
| Garage/Workshop | 500–1000 lx |
| Projector Room | 50–100 lx |
FAQs
Does using feet affect accuracy?
No. The calculator converts feet into meters automatically to provide precise lux values.
What if my room has irregular shape?
You can approximate by breaking it into smaller rectangles, calculate each area, then add them together.
Can I use this for projector setups?
Yes. For home theaters, aim for 50–100 lux to minimize glare and improve contrast.
Conclusion
Using lumens and room size in feet, our Lux Calculator helps you determine how much light reaches your space in lux. Whether you’re designing a living room, kitchen, or projector room, this tool ensures optimal lighting for comfort, safety, and energy efficiency.