Calculating the required lighting: lumens and lux per room

A carefully decorated room can still be unpleasant to live in if the lighting is poor. If it's too dim, you'll strain your eyes in the evening; if it's too harsh, the atmosphere disappears in an instant.

Calculating the lighting for a room means translating its surface area and usage into lumens, then distributing that total across several sources. The best approach is to define this figure before choosing a model from a lighting catalogue.

Lumens, lux, or watts: what should you really measure?

Watts indicate power consumption, not brightness. What actually provides light are lumens—the quantity of light emitted—and lux, which are the lumens received per square meter. To size the lighting for a room, you first estimate the total lumens, then the lux at ground level according to the activity.

A 9-watt LED often exceeds 800 lumens, whereas an old halogen bulb consumed 60 for a comparable result. Thinking in terms of watts no longer makes sense: the figure in lumens, printed on the packaging, is what you need to read. To get started, understanding lux helps distinguish between the two units.

The same light flux doesn't render the same way depending on the surface area. Five hundred lumens are enough above a coffee table; they get lost in a 30 m² living room.

The choice of bulb extends this calculation: base type, wattage in lumens, and color rendering. E27, E14, and GU10 bases appear most frequently on our product pages, and choosing your bulbs carefully avoids compatibility errors.

How many lux are needed per room?

Count on about 100 to 150 lux for ambient living room lighting, 150 to 200 lux in a bedroom, 300 lux in a kitchen, and up to 500 lux on a work surface or desk. Multiply these lux by the floor area to obtain the lumens to install.

The living room has multiple uses—reading, television, meals—therefore requiring multiple superimposed intensities rather than one fully lit ceiling. For a 20 m² living room aiming for 150 lux, plan for about 3,000 lumens distributed across several sources; a central living room light provides the foundation.

The formula is simple: desired lux multiplied by surface area equals the necessary lumens. For unconventional rooms or sloped ceilings, the detailed calculation method covers every step with numerical examples.

Once you know the figure, all that remains is to choose the model that reaches it without glare. The collection includes 19,747 references as of September 14, 2026, enough to cover any space; our designer lights are just as suitable for an entryway as they are for a large living room.

Hesitating between two power levels for the same room? The selection is reviewed by buyers, and their feedback can be viewed directly on the Designix Google listing.

How to distribute light and how many light points?

A single ceiling source leaves dark corners and harsh shadows. Distribute the light across three levels: general lighting, auxiliary points like reading lights or table lamps, and a few accents. Plan for one light point for every 4 to 6 m².

The central point remains the base of the general lighting, often above the living area. A well-sized ceiling light diffuses the main flux; other sources only serve to fill in what it doesn't reach.

Divide the surface area by five to estimate the number of fixtures. In the bathroom, the constraints change: according to a survey of 250 pendants in our catalogue as of September 14, 2026, 94% are IP20, reserved for use far from water sources, with IP65 taking over near the shower.

The color of the light matters just as much as its quantity. A warm white relaxes a living room, a cooler white brightens a kitchen or office; the color temperature is decided room by room.

Technically speaking, LED remains the logical choice for its longevity and low consumption: in that same survey of 250 pendants on September 14, 2026, 82% are labeled LED, and all 250 listings feature CE certification and a two-year warranty.

Once your lumen needs are estimated, you can talk to our team to refine the number of light points and the base types best suited to your room.