Luminous Flux Calculator
Calculate the lumen output your room needs for the right brightness when choosing new lights.
For even room lighting, area and desired illuminance (lux) matter most. This calculator determines the required luminous flux in lumens and an approximate number of LED bulbs.
Pro tips
- A typical LED bulb delivers 800-1,000 lumens at around 9-10 watts.
- Several smaller light sources often feel more pleasant than one large one.
Frequently Asked Questions
How many lumens does a living room need?
A normal living room usually feels comfortable at around 300 lux – for 20 m², that's about 6,000 lumens of total luminous flux, spread across several light sources.
How many LED bulbs do I need for a room?
Divide the required total luminous flux by a single bulb's lumen output (usually 800-900 lm) – the calculator above gives you an approximate bulb count.
Why does a room feel dark despite having many lumens?
Dark walls, furniture and floors absorb light – in darkly furnished rooms, it's worth calculating the luminous flux a bit more generously.
Does a kitchen need more light than a living room?
Yes, task areas like kitchens or offices are usually recommended at 500 lux, noticeably more than the 300 lux for cozy living-room lighting.