How many lumens for a living room?
3,450–6,950 lumens for 17.1 m² · 100–200 lux
A typical living room (4.5 × 3.8 m, 17.1 m²) needs 3,450–6,950 lumens from all its bulbs together, to reach 100–200 lux. Take about 30% of that from the ceiling, 50% from lamps and 20% from reading lamps. In bulbs, that is 5–9 of the 806-lumen kind, the brightness of an old 60 W bulb, at 2700–3000 K.
The range is wide on purpose. The low end is an evening with the lamps on; the high end is every light in the room at full, for cleaning or a board game. Fit the high figure and put the ceiling lights on a dimmer, and the room can do both.
A living room is the one room where most of the light should come from lamps, not the ceiling. Several small sources at different heights reach the corners, which is what makes a room look finished after dark.
Worked out for A living room 4.5 × 3.8 m (14 ft 9 in × 12 ft 6 in), 17.1 m² of floor, with a 2.4 m (7 ft 10 in) ceiling and light walls. Change the numbers
The working
- Floor area = 4.5 × 3.8 = 17.1 m².
- Room index = 4.5 × 3.8 ÷ (1.6 × (4.5 + 3.8)) = 1.29, with 1.6 m from desk height to the ceiling.
- Utilisation factor = 0.3 + 0.15 × 1.29, kept between 0.35 and 0.65 = 0.49.
- Target 100–200 lux for a living room.
- Lumens = 100–200 × 17.1 ÷ 0.49 = 3,450–6,950 lm (rounded to 50).
These are targets for every light on at once. You will rarely run them all together, so fit dimmers.
The rules, and their sources
Light levels for each room
Lighting guidance from the Society of Light and Lighting (SLL) and CIBSE gives about 100–200 lux for a lounge, 50–100 lux for a bedroom, 150–300 lux for a kitchen, 100–150 lux for a bathroom, and 250–300 lux for a home office, with 500 lux at the desk.
An industry guideline Sources: Spear Lighting, Technical section: residential lux levels from SLL LG9 (2013), BS EN 12464-1 and HSG38; office lux levels (checked 31 October 2026); CIBSE, SLL LG9 Lighting for communal residential buildings (checked 31 October 2026); CIBSE Code for Interior Lighting (1994), hotel table as reproduced on SlideShare (checked 31 October 2026).
How much bulb light reaches the room
Only part of a bulb's lumens reach the floor and tables: about half in a typical room with light walls, less with dark walls, a high ceiling or a small room. Bulb lumens ≈ lux × floor area ÷ utilisation factor.
An industry guideline Source: electricaltechnology.org, Lighting design calculation in a building, step by step (checked 31 October 2026).
Light in layers
A rule designers use: light a room from at least two or three sources at two or more heights, not from one ceiling light.
A rule designers use Source: Emily Henderson, 19 lighting combos and rules (checked 15 October 2026).
Average room sizes in homes built since 2010
In LABC Warranty's 2018 analysis of 10,000 listings, the average living room in a home built since 2010 was 17.1 m², against 24.9 m² in the 1970s; the average bedroom was 13.4 m².
A published study Sources: Which? (Garber, 14 Apr 2018), Shrinking homes: the average British house is 20% smaller than in the 1970s (checked 31 October 2026); Statista, Average living room sizes in new British houses 1930–2020 (checked 31 October 2026).
Other rooms
The same sum for each kind of room. The living room, kitchen and bedroom are the average sizes in homes built in recent years; a bigger room or darker walls need more.
| Room | All bulbs together | Light level |
|---|---|---|
| Living room4.5 × 3.8 m this page | 3,450–6,950 lumens | 100–200 lux |
| Living room4.5 × 3.8 m, dark walls | 4,350–8,700 lumens | 100–200 lux |
| Kitchen4 × 3.35 m | 4,250–8,550 lumens | 150–300 lux |
| Bedroom3.66 × 3.66 m | 1,400–2,850 lumens | 50–100 lux |
| Bathroom2.5 × 2 m | 1,250–1,850 lumens | 100–150 lux |
| Home office3 × 2.5 m | 4,400–5,250 lumens | 250–300 lux |
Change the numbers
Your sizes will differ. The room lighting calculator opens with these numbers filled in: change any of them and the answer, the working and the drawing follow.
Editorial notes
Worked out by the Snuug team on 12 November 2026 with the same code as the room lighting calculator, so the two cannot disagree. Every rule cites its source, with the date we last checked it. A rule designers use is a convention, not a study.
Other sources the calculator draws on:
- Commission Regulation (EU) 2019/2020, equivalence claims for non-directional light sources (470 lm = 40 W, 806 lm = 60 W, 1055 lm = 75 W, 1521 lm = 100 W), checked 31 October 2026
- Philips Hue, How far should recessed lights be from the wall? (ceiling height ÷ 2 apart; 50–60 cm from the wall at 2.4 m), checked 31 October 2026
- BLT Direct (7 May 2026), What is the difference between warm white, cool white and daylight LEDs?, checked 31 October 2026