What you need to know
- Measure lux where the task happens, not only in the middle of the room.
- Different tasks need different amounts and directions of light.
- More watts do not necessarily mean more useful light.
Use your own measurements
Use the linked BricoDato resource to check these inputs in your own situation. Lumens describe light produced by a source; lux describes illumination reaching a surface.
Lumens vs lux
Lumens describe the total visible light from a source. Lux describes how much of that light falls on each square metre of a surface.
Measure where you use the light
For a desk, measure at desk height; for a kitchen, at the worktop; for general lighting, take several points rather than relying on one spot.
Treat target values as guidance
Recommended lux values vary by task, age, contrast and local standards. Use measured comfort and task performance alongside generic ranges.
Improve distribution before adding power
Better luminaire placement, task lighting and lighter surfaces can improve useful illumination without simply installing higher-watt lamps.
Measure useful light at the task, not the ceiling
Lumens describe light produced by a source; lux describes illumination reaching a surface. Room geometry, the luminaire's direction and daylight can change a lux reading substantially.
Example to adapt
A 2 m² desk area at a hypothetical average 300 lux receives about 600 lumens over that surface under the simplified relation lux × m². That does not mean a 600-lumen bulb guarantees 300 lux on the desk: fixtures, reflection and geometry affect the result. Compare readings at the same desk points before and after changing lighting.
| Position | Measurement | Useful interpretation |
|---|---|---|
| Desk surface | Lux with task lighting on | Compare working light at the task |
| Room corner | Lux at matching height | Identify dark areas and unevenness |
| Daylight vs evening | Same point at both times | Separate natural and artificial contributions |
Checks before acting
- Measure at the working height and avoid shading the sensor with your body.
- Use several points and compare minimum as well as average illumination.
- Consider glare, colour rendering, flicker and colour temperature alongside brightness.
- Use published task-lighting guidance where work, accessibility or safety requirements apply.
Final check
Measure illuminance at the task surface: a desk, kitchen counter or reading area, not at the lamp diffuser. Take several readings across the workspace and repeat without daylight if artificial-light comparison is the goal. Lamp lumens describe total output; lux at a surface also depends on beam angle, distance, reflection and shadows.
- Measure at the task surface.
- Take several readings.
- Compare lumens and beam distribution.
- Improve placement before increasing wattage.
Keep a small job sheet
Note date, time, daylight, meter, measurement height and point-by-point lux values.
Turn the guide into a decision
Record sensor position, hour and light setting to make later comparisons meaningful. Improving luminaire placement or reducing glare may help more than installing brighter lamps; confirm any professional or workplace lighting requirements using the applicable standard.