Lighting calculators

How much light does your room need?

Lumens are the amount of light, watts are the consumption — the two are not the same. Enter your room's details and we'll tell you how much total luminous flux you need, and how best to split it into three layers.

Guide values for a 15 m² room

Lighting needs per room, the total luminous flux needed for a 15 square-metre room, and the recommended colour temperature.
Room	Illuminance	Total luminous flux	Colour temperature
Living room	150 lux	2,500 lm	2700–3000 K
Dining room	175 lux	2,900 lm	2700 K
Kitchen	300 lux	4,950 lm	3000–4000 K
Bedroom	125 lux	2,050 lm	2700 K
Bathroom	250 lux	4,150 lm	3000–4000 K
Study	300 lux	4,950 lm	3000–4000 K
Children's room	200 lux	3,300 lm	3000 K
Hallway, corridor	150 lux	2,500 lm	2700–3000 K
Terrace, outdoors	75 lux	1,250 lm	2700 K

For a room with light walls and a 2.5–3.0 m ceiling. With dark surfaces you need 20–30% more, and for users over 60 about half as much again.

How we calculate: illuminance (lux) × floor area (m²), then multiplied by the corrections for ceiling height and wall colour. Lux tells you how much light reaches a surface, lumens how much the light emits — which is why the lumens you need depend on the size of the room. The result is a design guide value, not a measurement: the real illuminance also depends on where the lights are placed and how they distribute light.

Chandelier size calculator

Chandelier size is a question of proportion, not taste. There are two separate cases: in the middle of a room, the light should match the room's proportions; above a dining table, it should match the table — and the two often give very different sizes.

Centre of the room — sizing table

Room sizes and the chandelier diameter in proportion to them.
Room	Recommended diameter	Range
3,0 × 3,5 m	50 cm	45–60 cm
3,5 × 4,0 m	60 cm	55–70 cm
4,0 × 4,5 m	70 cm	60–75 cm
4,0 × 5,0 m	70 cm	65–80 cm
4,5 × 5,5 m	80 cm	70–90 cm
5,0 × 6,0 m	90 cm	75–100 cm

Diameter ≈ (length + width) × 8, in centimetres. If people walk underneath, the bottom of the light should be at least 210 cm above the floor.

Above a dining table

Table width, recommended light diameter and hanging height above the table top.
Table width	Light diameter	Height above the table top
80 cm	40–55 cm	70–85 cm
90 cm	45–60 cm	70–85 cm
100 cm	50–65 cm	70–85 cm
110 cm	55–75 cm	70–85 cm
120 cm	60–80 cm	70–85 cm

Above a table, measure from the table top, not the floor — nobody walks there, and the light must stay below eye level so it doesn't dazzle.

Two common mistakes: the first is choosing the light above the dining table by room size — that is how a 4×5 m room ends up with a 70 cm chandelier above a 90 cm table, which is out of all proportion. The second is measuring the hanging height from the floor even above a table; there, the right reference is the table top.

Light colour simulator

Luminous flux is the quantity, colour temperature is the quality. The same 3,000 lumens feel homely at 2,700 kelvin and harsh at 6,500 — and this is the biggest uncertainty when buying, because you can rarely compare them in a shop.

Warm white 2700 K — The colour of the classic incandescent bulb. Living room, bedroom, dining room — at home this is most often the right choice.

The scale, point by point

Colour temperatures, their names and recommended uses.
Kelvin	Name	Where it belongs
2200 K	Candlelight	Very warm, amber. A restaurant or bar atmosphere. Too dim for reading, but excellent as evening mood lighting.
2700 K	Warm white	The colour of the classic incandescent bulb. Living room, bedroom, dining room — at home this is most often the right choice.
3000 K	Warm	A shade crisper, but still homely. Kitchen, bathroom, children's room.
4000 K	Neutral white	Study, workshop, garage. In a living room it feels cold, and it can be jarring in the evening.
5000 K	Cool white	Industrial and commercial spaces. Almost never justified in living spaces.
6500 K	Daylight	The colour of the midday sky. Not for home use: harsh, and in the evening it makes it much harder to fall asleep.

What this simulation shows, and what it doesn’t: it conveys the difference faithfully, but it is not a colour-accurate measurement — your screen’s own white balance plays a part too. Before buying, look for the kelvin value on the packaging, and use the same one throughout a room where you can: two different colour temperatures in one space are more jarring than either on its own.

Bulb replacement helper

Watts measure consumption, not light. If you start from the wattage of the old bulb, it is easy to get it wrong — this table tells you the real equivalent based on luminous flux.

Conversion table

Wattage and luminous flux of incandescent bulbs, and the matching LED wattage.
Old bulb	Luminous flux	LED equivalent
25 W	~230 lm	2–3 W
40 W	~430 lm	4–6 W
60 W	~730 lm	6–10 W
75 W	~950 lm	8–12 W
100 W	~1,350 lm	11–17 W
150 W	~2,200 lm	17–28 W

The LED range assumes an efficacy of 80–130 lm/W. On the packaging, always look for the lumen value, not the watts.

What to watch out for when swapping: the maximum wattage marked on the light fitting refers to incandescent bulbs — with LED it is practically never the limit. What does matter is the colour temperature (2,700–3,000 K at home), the colour rendering (CRI above 90), and whether it is dimmable if it goes on a dimmer. Not every LED is, and a non-dimmable LED on a dimmer flickers or fails.