What is lumen?

The topic of lighting may not be something you think about (or talk about) on a daily basis (unless you are completing renovations, and then it becomes a topic of conversation you get sick of pretty quickly), but when you need to change a light bulb or are looking into some new lighting options for your home or office, it is good to have a basic knowledge of what you are looking for.

We, therefore, thought we'd put some information together about lumens, as well as watts and lux, to help you along. If you have any further questions or would like to speak to an electrician regarding a lighting issue or project, give Alltronic Electrical a call at 07 3353 3248 and we can help.

Lighting Definitions

To make things as easy as possible to understand, take a look at the following definitions of watt, lumen, and lux to start things off.

What is a lumen?

Lumen is a measurement of the amount of light that is created by a light source. The light must be visible to the naked eye, and is denoted by the letters 'lm'. Lumens are generally used to figure out how bright a light is... so, in basic terms, lumens equal brightness.

What is lux?

The next measurement to consider is lux - which is used to measure light intensity and is sometimes known as 'illuminance' or 'illumination'. Another way to explain lux is the amount of light that is expelled in a particular area.

What is a watt?

Last, but certainly not least, is watts. Watts is the most well-known measurement when it comes to lighting - you may know it is a 'W' on light packaging - and the general population believe watts relate to brightness... which isn't entirely true. Watts are connected to energy consumption - that is, how much electricity a light utilises.

The reason for the incorrect understanding when it comes to watts and brightness stems from the use of incandescent light bulbs in the past. Coincidentally, the amount of light an old incandescent light bulb used to emit was the same number as the wattage (even from differing manufacturers), which is why many people between W = brightness. With the evolution of energy-efficient lighting, however, lights do not need nearly as many watts to achieve higher brightness levels, meaning the numbers aren't the same as they used to be.

For example, a 42W halogen bulb has the same brightness (lumens) as an LED that uses 10 watts. Lower wattage means lower energy bills and fewer carbon emissions, meaning better for the environment (and more cost-effective).

How do they all compare?

So, how do lumens, watts and lux compare to one another? They are all used to explain different aspects of lighting, however, there are some comparisons that can be made.

Lumens to Watts

Firstly, there are lumens and watts. They don't exactly have an 'equal' equation, however, you may see some bulb packaging (mostly incandescent bulbs) that says 'Equivalent Watts' written on them. When this is written, it is generally referring to the relationship between watts and lumens - for example, 900lm equates to a 60W incandescent light bulb, as well as a 15W LED light or fluorescent bulb.

A few other comparisons include:

1125lm = 75W incandescent light bulb watts = 18.75W fluorescent/LED watts.
1500lm = 100W incandescent light bulb watts = 25W fluorescent/LED watts.
1250lm = 150W incandescent light bulb watts = 37.5W fluorescent/LED watts.
LEDs produce around 80 lumens per watt (lm/W), compared to 14 lm/W produced by a similar halogen. For perspective, the higher the lm/W, the more energy efficient a bulb is.
A 60W incandescent bulb emits 800lm, which is the same as a 42W halogen, a 13W CFL or a 10W LED.

Lux vs Lumens

1 lux = 1 lumen/m²

The equation of 1 lux = 1 lumen/m² relates to the intensity of light that is being emitted in a particular area. Remember that lumens relate to the brightness of a light, whereas lux is in relation to the output light levels in a particular area.

An example is probably the best way to go here - if there is a measurement of 1,000 lumens in a 1m² area, there is an illumination level of 1,000 lux. If you take the same 1,000-lumen measurement but spread it over 10m², there will be an illumination level of 100 lux.

Talk to your local lighting professional as to the best light specifications for your particular area, as this can be a little tricky sometimes!

Some lighting comparison examples

So, how does everything fit together? It isn't a simple answer of one equals another, however, to make things a little easier to envisage, here are a few comparisons and a table setting out the above information:

Power (watts)
	Traditional Incandescent	Halogens (mains voltage)3	CFL	LED
	25	18	4-6	3-4
	40	28	7-9	5-8
	60	42	11-14	8-12
	75	52	14-17	11-17
100	70	19-23	15-23

This table is courtesy of Energy Rating. This table is a guide only, as bulbs can differ depending on the manufacturer.

Your lighting experts in Brisbane

If you have any questions regarding lumens, lighting or how Alltronic Electrical can assist with your home or office lighting, give us a call today at 07 3353 3248.

Energy Rating (Lumens to Watts): http://www.energyrating.gov.au/lighting/lumens-watts

Wikipedia (Lumens): https://en.wikipedia.org/wiki/Lumen_(unit)