You read "50 lux" on a spec sheet, in a standard or in a lighting tip, and the figure means nothing. That is normal: unlike the lumen, lux never appears on a bulb box. Yet both measure the same light, seen from two different places. Here is what 50 lux actually represents, how to convert it into lumens for your room size, and when that level is the right one.
To size every room in the house, this guide completes our how many lumens per room reference.
The answer in one line
50 lux is 50 lumens per square metre. One lux is, by definition, one lumen spread over one square metre. So to find the lumens you need, simply multiply 50 by the floor area you want to light.
For a 12 m² room, that gives 600 lumens in total. On paper a single 600-lumen lamp would do it — in practice you always spread that light across two or three sources, to avoid one bright spot in the middle of the ceiling.
Lux, lumens, watts: the difference in a minute
Three units come up constantly, and only one of them appears on your bulb packaging.
| Unit | What it measures | Where you find it |
|---|---|---|
| Lumen (lm) | The light emitted by the lamp, in every direction | On the bulb box |
| Lux (lx) | The light received by a surface, at one precise spot | In standards, on a light meter |
| Watt (W) | The electricity consumed, not the light | On your bill |
The simplest picture: the lumen is how much water the watering can pours out. The lux is how much water each square metre of lawn receives. The same can delivers plenty of lux on a small patch, and very little across a big garden.
That is why a lamp can never be sold "in lux": its lux value depends on the room, the height and the distance. The manufacturer only knows the lumens. If watts still confuse you, our guide to LED, halogen and incandescent sorts it out.
50 lux converted into lumens, area by area
The formula fits on one line: lumens = lux × area in m². Here is the result for the most common room sizes.
| Area | For 50 lux | Example room |
|---|---|---|
| 5 m² | 250 lumens | Small hallway, dressing room |
| 8 m² | 400 lumens | Corridor, small spare bedroom |
| 10 m² | 500 lumens | Child's bedroom |
| 12 m² | 600 lumens | Standard bedroom |
| 15 m² | 750 lumens | Large bedroom |
| 20 m² | 1 000 lumens | Compact living room |
| 25 m² | 1 250 lumens | Large living room |
Those figures are the theoretical calculation. In a room with dark walls, high ceilings or opaque shades, allow 20 to 30 % more lumens to get the same feeling: part of the light is absorbed before it reaches the floor.
Where 50 lux is right, and where it falls short
50 lux is an ambient level, not a working level. It is the light of an evening, of a corridor at night, of a living room at the end of the day when only the accent lamps are on. You can move around, talk and watch a film perfectly well. You cannot read for long without tiring.
| Level | Situation | How it feels |
|---|---|---|
| 0,25 lux | Full-moon night | Shapes visible, colours gone |
| 20 lux | Night light, moving around after dark | Just enough not to bump into things |
| 50 lux | Dimmed ambience, relaxed evening | Warm, restful |
| 150 lux | Bedroom, general light | Comfortable without being bright |
| 300 lux | Reading corner, dining table | Comfortable for reading |
| 500 lux | Worktop, desk | Precise, no visual effort |
| 1 000 lux | Outdoors, overcast day | Clear, open light |
| 100 000 lux | Full summer sun | Dazzling |
Two lessons. First, the gap between indoors and outdoors is enormous: the best-lit room in your home is still twenty times darker than a grey day outside. Second, 50 lux is plenty in the evening, because the eye adapts. Comfort does not come from the quantity of light, but from its consistency with the time of day.
That is exactly what a dimmer is for: going from 300 lux at dinner to 50 lux for the evening, with the same lamps. Our guide to the dimmer switch explains how it works.
How to check your 50 lux at home
No professional kit needed. A light meter app on a smartphone gives a close enough reading to find your bearings, as long as you follow three rules.
Lay the phone flat, sensor facing up, on the spot that matters: the table, the worktop, the corridor floor. What you measure is the surface receiving the light, not the lamp.
Measure at night, with the blinds closed. During the day, daylight distorts everything: even under cloud, a window brings in several hundred lux.
Take three readings and average them: under the lamp, halfway across, and in a corner. The spread between the three tells you more than the figure itself. A ratio of 1 to 10 between the brightest and darkest point signals a badly distributed room, even when the average looks right.
Two lamps built for this level
An ambient level calls for diffused light, not a beam. Here are two lamps whose shade softens the source, to use as accent lighting in a living room or bedroom.
Japora — Japanese lantern on a wooden base
The Japanese lantern revisited: a twisted shade lined with fine vertical ridges spreads a soft light that ripples across the walls, set on a light wood base.
- Table lamp
- Japanese style
- Light wood base
- Entry price
Temora — Rice paper lamp, 60 cm
The Japanese art of rice paper in a generous 60 cm silhouette: a soft, glare-free light that dresses a room. Standard E27 fitting, compatible with any bulb.
- Table lamp
- Rice paper
- 60 cm
- E27 fitting
Frequently asked questions about lux
How many lumens is 50 lux?
50 lumens per square metre. For the total, multiply by the area: 600 lumens for 12 m², 1 000 lumens for 20 m².
What is the difference between lux and lumens?
The lumen measures the light emitted by the lamp, the lux the light received by a surface. The same 500-lumen lamp gives 100 lux over 5 m² and only 25 lux over 20 m².
Is 50 lux enough to read by?
No. Comfortable reading needs 300 lux on the page, six times more. 50 lux suits the general ambience of a room, with a dedicated reading lamp alongside.
How do you measure the lux in a room?
With a light meter app on a smartphone, laid flat on the surface concerned, at night with the blinds closed. Take three readings and average them.
How many lux in a living room?
Between 100 and 300 lux for general lighting depending on the moment, and 50 lux for evening ambience. The room-by-room detail is in our guide to how many lumens for a living room.
50 lux, in short
50 lux equals 50 lumens per square metre: multiply by your area and you have the total to install, meaning 600 lumens for a 12 m² room. It is an ambient level, the light of a good evening, to be topped up with stronger sources wherever you read or work. To size the whole house, open our how many lumens per room reference.
The Lumora tip
Do not look for the right lux figure for a whole room: look for it per use. A living room works beautifully with 50 lux of ambience and a reading corner at 300 lux, two metres apart.
