What is a lumen?

What is a lumen?

So, what is a lumen? Considering the fact that you are on this page to begin with, you are likely asking yourself this exact question. You’ve probably heard of watts when it comes to lighting, and maybe even lux, but there’s also lumens too. So, what’s it all about?


A few lighting definitions

Lumen definition

When it comes to lumen, things can get a little technical however we will try to keep things as simple as possible. Lumens, which are denoted by ‘lm’, are a standardised unit of measure that quantify the amount of light visible to the human eye that is produced by a light source, like a lamp or an LED light. Another way to think about it is like this – lumens are the way to figure out how bright an LED light or light bulb is.

Lumens = Brightness!

What is a watt?

A watt, denoted by a ‘W’, is likely the most common unit you have come across when looking at lighting. Watts are generally considered a measure of brightness, which isn’t technically correct. Watts are actually a measure of energy consumption – so, in essence how much electricity a particular light bulb uses. In the past, coincidentally most old incandescent bulbs put out the same amount of light (lumens) as wattage, even when they were from different brands, which is why lumens and watts can get confused. These days however, light bulbs can produce similar brightness using way less electricity, meaning they are cheaper to run.

For example, a 42 W halogen bulb has the same brightness (lumens) as an LED that uses just 10 watts. Lower wattage means lower energy bills – and less carbon emissions. Better for your wallet and better for the environment!

What is lux?

Finally, there is lux. Lux is a measure used to quantify the light level intensity, which is sometimes referred to as ‘illuminance’ or ‘illumination’. Lux is used to measure the amount of light output in a given area.

Light Bulb

Lux vs Lumens

What about lux vs lumens? When it comes down to it, 1 lux = 1 lumen/m², designating the light intensity in a particular area. Lux is used to measure the amount of light output in a given area, whereas lumen is the measurement of brightness of a light.

As an example, 1,000 lumens located in one square metre lights up that square metre with an illuminance level of 1000 lux. The same 1,000 lumens, but spread out over ten square metres, produces an illuminance level of only 100 lux. Have a chat with your local professional as to the best levels for your home or office.

Lumens to watts

So, how many lumens in a watt? It isn’t quite as simple as one equals the other, however on some incandescent bulb packing there is an ‘Equivalent Watts’ note on them. For example, 900 lumens (lm) is the equivalent of 60W incandescent light bulb watts and 15W fluorescent/LED watts. A few other conversions include :

  • 1125 lumens (lm) is the equivalent of 75W incandescent light bulb watts and 18.75W fluorescent/LED watts
  • 1500 lumens (lm) is the equivalent of 100W incandescent light bulb watts and 25W fluorescent/LED watts
  • 1250 lumens (lm) is the equivalent of 150W incandescent light bulb watts and 37.5W fluorescent/LED watts

A few facts courtesy of Energy Rating :

  • An efficient LED produces 80 lumens per watt (lm/W), compared to 14 lm/W of an equivalent halogen. To put this into perspective, the higher the lm/W the more energy efficient the lighting is.
  • An old 60W incandescent bulb puts out 800 lumens (lm), which is the same as a 42 W halogen, 13 W CFL or 10 W LED

The following table sets out the comparison between lumens and watts :

Output (lumens)Traditional incandescent (watts)Halogens (mains voltage) (watts)CFL (watts)LED (watts)
25184 – 63 – 4
40287 – 95 – 8
604211 – 148 – 12
755214 – 1711 – 17
1007019 – 2315 – 23

This table is courtesy of Energy Rating: http://www.energyrating.gov.au/lighting/lumens-watts. This table is a guide only, as bulbs can vary between different manufacturers.

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If you have any further questions regarding lumen or lighting, give Captain Cook Electrical a call on 0481 134 679 or complete an online job booking form now. We are the experts in electrical and lighting solutions across Sydney, so get in contact now!

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Resources :

Wikipedia (Lumen (unit)) : https://en.wikipedia.org/wiki/Lumen_(unit)Energy Rating (Lumens to Watts) : http://www.energyrating.gov.au/lighting/lumens-watts


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