Lumens to Lux Calculator

Written byOleh Soloninupdated 25 September 2026

Direction

Luminous flux, lm

Area, m²

Result

Illuminance, lx66.67
Luminous flux, lm1,000
LED lamps at 75 lm/W, W13.3
Incandescent lamps at 13.8 lm/W, W72.5
Against the SP 52.13330 norms
below the 100 lx the Russian code SP 52.13330 sets for a corridor or bathroom
Area, m²15
WorkingE = Φ ÷ A = 1,000 ÷ 15 = 66.67 lx

Lumens describe the lamp, lux describe the surface

Converts luminous flux to illuminance over an area and back, compares the result with the home lighting norms of Russia's SP 52.13330 and shows the wattage of LED and incandescent lamps at the efficacies Wikipedia gives.

A lumen measures how much light a lamp gives out; a lux measures how much of it lands on each square metre: 1 lx = 1 lm/m². A 1,000 lm lamp whose light falls evenly on 15 m² gives 66.67 lux.

The formula assumes all the light reaches the surface. In a room, walls, ceiling and the fitting absorb some of it, so choosing lamps is done with the room lighting calculator, which adds the maintenance factor from SP 52.13330.

How to use

Choose the direction: lumens to lux or lux to lumens.
Enter the lamp's luminous flux or the illuminance you need, and the area.
Read the result, how it compares with the SP 52.13330 norms and the wattage of lamps giving that flux.

Illuminance from lamps of different output

Each row is a separate run. Wattages assume 75 lm/W for LED lamps and 13.8 lm/W for incandescent ones.

All rows come from the calculator on this page.
Flux	Area	Illuminance	Against SP 52.13330	LED, W	Incandescent, W
400 lm	10 m²	40 lx	below the 100 lx corridor norm	5.3	29
1,000 lm	10 m²	100 lx	the corridor and bathroom norm	13.3	72.5
1,000 lm	15 m²	66.67 lx	below the 100 lx corridor norm	13.3	72.5
2,000 lm	10 m²	200 lx	the living-room norm	26.7	144.9
5,000 lm	10 m²	500 lx	the office norm	66.7	362.3

Where the watts and the norms come from

Wikipedia's "Luminous efficacy" article gives 230 V LED screw-base lamps 75–217 lm/W, compact fluorescents 46–75, 100 W halogen lamps 16.7 and 100 W incandescent lamps 13.8 lm/W. The calculator takes the low figures, so its wattages lean high: an LED lamp of the same output may well draw less.

The norms it compares with are Russian — table L.1 of SP 52.13330.2016 as amended by Amendment No. 2, in force since 29 January 2022: 200 lx for living rooms and kitchens and 100 lx for corridors, bathrooms and toilets, measured on the floor, and 500 lx for offices at 0.8 m. Other countries set their own figures.

What this calculator shows

Illuminance in lux, or the luminous flux needed to reach it
The LED and incandescent wattage that would deliver that flux
What the resulting light level feels comparable to

What to keep in mind

Assumes light spread evenly across the area; a real fitting throws a pool and the edges of the room will be darker.
Efficacy uses the low end of the figures in English Wikipedia's "Luminous efficacy" article for 230 V lamps: 75 lm/W for LED, 46 for compact fluorescent, 16.7 for halogen and 13.8 for incandescent. These are not market averages: the low end errs towards more watts.

FAQs

How many lux does a 1,000-lumen lamp give?

It depends on the area: 100 lx over 10 m² and 66.67 lx over 15 m², if the light falls evenly on the surface.

How many lumens do I need per square metre?

As many as the lux you want: a living room under SP 52.13330 needs 200 lm per square metre of floor, a corridor 100. An 18 m² living room needs 3,600 lm before losses.

What LED replaces a 100 W incandescent bulb?

A 100 W incandescent lamp at 13.8 lm/W gives about 1,380 lm. An LED lamp at 75 lm/W needs 18.4 W for that, one at 150 lm/W 9.2 W.

What is the difference between a lumen and a lux?

A lumen is a lamp's light output; a lux is the illuminance of a surface. The same 800 lm lamp gives 80 lx over 10 m² and 40 lx over 20 m².

Why is the real illuminance lower than the sum?

Walls, ceiling and the fitting absorb part of the light, and lamps dim with age. For choosing lamps SP 52.13330 adds a maintenance factor — 0.71 for living rooms, 0.7455 with LED fittings — which the room lighting calculator applies.

How do I convert lux to lumens?

Multiply by the area: 300 lx over 12 m² is 3,600 lm, 100 lx over 6 m² is 600 lm.

Worked example

A lamp in a 15 m² room

Input: 1,000 lm over 15 m²

Output: 66.67 lx — below the 100 lx corridor and bathroom norm

Note: An LED lamp giving that flux at 75 lm/W draws 13.3 W.

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