Almost all lamp specifications nowadays include a number in lumens. This indicates how much light the lamp produces. In the past, a lamp’s wattage was often the only specification provided, but nowadays it says much less about the light output. So how exactly does it work?

What does lumen mean?

Lumen (lm) is the unit of luminous flux, or a measure of the total amount of visible light emitted by a lamp. It specifically refers to visible light because some lamps also emit, for example, infrared light or heat in addition to visible light.

When most lamps were still incandescent bulbs, the amount of light was expressed in watts. Nowadays, however, there are so many different types of lamps that we have switched to lumens. This makes it easy to compare different lamps (halogen lamps, LED lamps, energy-saving lamps). Wattage only indicates the lamp’s electrical power consumption, so it no longer says very much about its light output. A 50-watt halogen lamp does not emit as much light as a 50-watt LED lamp.

Comparing lumens with watts

To make it easier to get used to using lumens, we compare a lamp’s luminous flux in lumens with the power in watts of an incandescent bulb. For example, an LED lamp’s packaging may state that it produces 470 lumens, equivalent to a 40-watt incandescent bulb. In the table below, we compare the number of lumens produced by an incandescent bulb with the corresponding wattage.

How many lumens do I need?

This table applies only to bulbs or omnidirectional lamps, not spotlights. The light in a spotlight’s beam is more concentrated. Therefore, a spotlight needs fewer lumens than a bulb to provide the same amount of light in a particular place. However, a spotlight only shines on a small area, while an omnidirectional lamp often illuminates the entire room. The number of lumens you need therefore also depends on the shape of the light beam produced by the lamp in question.

To give you an idea of luminous flux in lumens: 800 lumens is more than enough to illuminate a room. A table lamp produces an average of approximately 200 lumens. Several mood lights together should not produce much more than 100 lumens each. As always, however, the number of lumens you need mainly depends on the placement and use of the space. If you have a light fixture that hangs very high, you naturally need more lumens to see properly than when using a desk lamp. That is why it can sometimes be useful to try out different lamps or have a lighting plan drawn up.