Room lighting calculator
Lighting levels are measured in lux — lumens per square metre. Multiply the area by the recommended level for the room and divide by the lumens of one bulb.
Your measurements
Result
- Light output needed
- 2,250 lm
- Light sources needed
- 3 pcs
Guide values for general lighting; work areas (kitchen worktop, desk, mirror) need extra local light.
How the calculation works
- Recommended level depends on the room: about 100 lux in a bedroom, 150 in a living room, 200 in a bathroom, 300 in a kitchen and home office.
- Light output needed (lumens) = room area × lighting level (1 lux = 1 lumen per m²).
- Light sources = lumens needed ÷ lumens of one source, rounded up.
Worked example
A 15 m² living room needs 15 × 150 = 2,250 lumens. With 1,000 lm bulbs you need 3 light sources.
What the calculator assumes
- The values are for general lighting with an ordinary ceiling and light-coloured walls.
- Lumens are on the bulb's packaging; a ~10 W LED bulb gives around 800–1,000 lm.
When to adjust the result
- Work areas (kitchen worktop, desk, bathroom mirror) need extra local light.
- Dark walls, high ceilings and opaque shades absorb light — add one source.
Layering light in a room
One ceiling light rarely lights a room well. Combine general light, task light where you read, cook or work, and a few accent lights for atmosphere. Dimmers on the main circuits let the same fittings serve both bright and relaxed moods.
Colour temperature changes the feel: warm white (2,700–3,000 K) suits living rooms and bedrooms, neutral white (3,500–4,000 K) suits kitchens, bathrooms and workspaces. Check the colour rendering index too — CRI 90 or above shows colours and skin tones naturally.
Frequently asked questions
How many lumens does a room need?
Area × lux: a 15 m² living room at 150 lux needs about 2,250 lumens.
How many lumens is a 60 W bulb?
An old 60 W incandescent gave about 700–800 lm; an LED of about 8–9 W replaces it.
How many lumens for a living room?
Roughly 100–150 lumens per m² for general light, plus task lighting where you read.
Warm or cool white?
Warm white for relaxing rooms, neutral white for kitchens, bathrooms and offices; avoid mixing very different colour temperatures in one room.