Lighting buying guide
Lumens, watts and lux: how to compare brightness
Lumens describe emitted light. Watts describe power consumption. Lux describes the light reaching a surface. These units cannot be used interchangeably.
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What each unit tells you
| Unit | What it describes | How to use it |
|---|---|---|
| Lumen (lm) | Light output emitted by a source or luminaire. | Compare light output, checking what the declared value covers. |
| Watt (W) | Electrical power consumption. | Assess energy use, not brightness on its own. |
| Lux (lx) | Illuminance on a surface; one lumen per square metre. | Assess the light reaching a worktop, desk or other area. |
| lm/W | Luminous efficacy. | Compare output per watt under comparable conditions. |
Why there is no fixed watt-to-lumen conversion
Different technologies and models produce different light outputs from the same power. An LED’s wattage alone is not enough to calculate its lumens. Compare the manufacturer’s actual declaration.
Approximate references for traditional incandescent lamps are shown below. They are useful reference points, not a formula for every LED and not a guarantee of the same effect through a shade.
| Traditional incandescent reference | Approximate output |
|---|---|
| 40 W | 470 lm |
| 60 W | 800 lm |
| 75 W | 1,050 lm |
| 100 W | 1,500 lm |
Check whether the value describes the bulb or the fitting
Shades, lenses and the fitting itself affect useful output and distribution. A sum of nominal bulb outputs is not necessarily the output of the complete luminaire. Check whether the manufacturer specifies the source or the complete product.
How much light and energy will you need?
There is no single lumen figure suitable for every room of a given size. Height, finishes, beam distribution and the activity matter. For detailed planning, request a lighting assessment.
Energy in kWh = power in watts × operating hours ÷ 1,000. For example, a 10 W source operating for 1,000 hours uses 10 kWh. To estimate cost, multiply by your own applicable electricity price.
Questions before buying
Will a higher-wattage LED always be brighter?
No. Compare lumens and the lighting arrangement, not watts alone.
Do more lumens always mean a better choice?
No. The light should suit the task and distribution without causing unnecessary glare.
Prepared by twoje-lampy.live · updated 24 October 2026.
Technical references: www.philips-hue.com, energy-efficient-products.ec.europa.eu.