What Are Lumens, Candelas and Lux?

Lumens, Candelas and Lux are measurements you may have seen on light bulb packaging or specifications, but what do they actually mean?

How can understanding these help you choose the right bulb? Knowing what these measurements are can really help when choosing a bulb. By understanding what light you want from a bulb, you can make an informed decision when it comes to making your purchase.

Lumens

Lumens in its simplest form, is a measurement of how much light is created from a source. The higher the lumen the brighter the light source is. It is a measurements of light that is required by law and is found on all light packaging. It is a great indication of brightness and can help find the right bulb for your requirements. It is often the most convenient measurement to use when comparing the brightness between bulbs (other than turning two bulbs on side by side).

Candelas

A Candela is a measurement of light intensity. It is based on the principle that the light of one candle is one Candela, therefore 20 candles would equate to the brighter light of 20 Candela. Think: How would 1 candle light a room in comparison to 20 candles in the same room?

This measurement can be used to work out the amount of useful light given from a spotlight. Brightness is needed but it is only useful if enough of that light is reaching the object you wish to illuminate. A spotlight with a high lumen output but low Candela value, would be bright at the source but would be no good in a room with a high ceiling as the source would not reach the lower areas of the room.

Lux

Lux is the measure of illumination on a given surface at distance. It is generally defined by how bright the light is on a surface at a defined distance. 1 Lumen falling on 1sm= 1 Lux.
Lux will generally decrease as distance increases from light source.

With an understanding of these three measurements it can become easier to understand lamp labelling. With LED lights it really does help to have a good understanding of the varying measurements and fundamental workings of an LED because unlike traditional incandescent where we could buy based solely on the wattage, with LED light bulbs there are many more thing to consider. If you are still worried or baffled by the minefield of lighting jargon fear not, most electricians will have a good understanding of lighting, or if you are working on a unique or quirky project, you could always consider hiring professional lighting designer. They will often consult your lighting needs based on the atmosphere you wish to create of the brightness you would like to achieve in a given are. They can provide specifications for you to use and compare when exploring different types of bulb.