How to Use the Room Lighting Count Calculator
When installing or replacing lights, guessing how many you need often leads to a room that's too dim or unnecessarily bright. This calculator uses your room's floor area and a target brightness level (lux) to work out the total light output required, then divides that by the lumen rating of a single light to tell you how many you need.
Lux measures how much light lands on a given area, while lumens measure the total light a fixture produces. Multiplying your room's area by the target lux gives the total lumens needed for the whole room; dividing that by a single bulb's lumen rating gives the light count. Typical targets are about 100 lux for bedrooms, 150 lux for living rooms, 300 lux for kitchens and study areas, and 500 lux for workshops.
Ceiling height, fixture placement, and wall color all affect how bright a room feels in practice, so treat the calculated count as a minimum and lean toward a bit more coverage rather than less. If your fixtures are dimmable, it's often smart to install slightly more lights than the minimum and dim them to taste.
Frequently Asked Questions
Yes — bedrooms typically target around 100 lux, living rooms 150 lux, study/kitchen areas 300 lux, and workshops 500 lux. Pick the value that matches your room's use.
Check the packaging or product page for the lm (lumens) value. Most household LED bulbs range from about 800 to 1,500 lumens.