What does the number of lumen of a lamp mean?
What do you pay attention to: lumen or wattage?
When you used to choose a lamp, it was a lot simpler than it is now. You looked at the wattage and the fitting and that's how you chose your lamp. Manufacturers thought that by indicating the wattage, they gave an indication of the light output. That's not how it works. The wattage says something about the energy consumption, not about the light output. Do you want to know how much energy a lamp uses per second? Look at the wattage. When you want to know the light output of a lamp, you look at the number of lumens. With lumens, we express the light intensity per wattage.
What are lumens?
If you compare different types of lamps like an incandescent light bulb and an LED light bulb based on the wattage, it's actually comparing apples and oranges. An LED light bulb is much more energy-efficient than an incandescent light bulb, so the wattage is a lot lower. How do you compare an incandescent or halogen light bulb to an LED light bulb? You look at the number of lumen. Lumen is the brightness a light bulb emits per wattage. The more lumens you have, the higher the wattage and vice versa. But that's limited within 1 type of light bulb, of course. Otherwise, you'll circle back to the apples and oranges.
Comparison
| Wattage | Light bulb | Halogen light bulb | Energy-saving light | LED light bulb |
|---|---|---|---|---|
| 15W | 225 lumens | 300 lumens | 900 lumens | 1350 lumens |
| 25W | 375 lumens | 500 lumens | 1500 lumens | 2250 lumens |
| 40W | 600 lumens | 800 lumens | 2400 lumens | 3600 lumens |
What exactly is lux?
Lux is the amount of light that shines on a certain surface. When you distribute a light source of 100 lumens over 1m2, the light illuminates your surface with 1000 lux. But when you distribute the same amount of lumens over 10m2, the light source only illuminates your surface with 100 lux. If you need a specific light intensity for a certain area like a workplace at the office, it's better to check the lux. For example, 500 lux is the standard for a workplace.
