The amount of light emitted from or reflected off an object is called its luminance-commonly referred to as brightness. They are described by their energy or, inversely, by their wavelength. The radiation of light is made up of sub-atomic particles (photons), which have no mass but are simply carriers of energy. b. Electromagnetic radiation of any frequency or wavelength.īeyond this basic definition, we have tools and language to precisely describe, quantify, and analyze the electromagnetic waves (visible and invisible) that are all around us, emanating from the sun, from flames, and from artificial sources such as light bulbs. a. Electromagnetic radiation that is visible, perceivable by the normal human eye as colors between red and violet, having frequencies between 400 terahertz and 790 terahertz and wavelengths between 750 nanometers and 380 nanometers. Also called visible light. If you'd like to know more, check out our blog What is Lux Level? for more information on lux levels.The American Heritage Dictionary tells us: Lumens and Lux are both readily available pieces of information which should be visible on the packaging of most bulbs. When planning your lighting setup, this is important for working out how many light bulbs you might need to adequately light a room.īoth of these figures are important to help create a well informed purchase, and to get the most out of your lighting. However, lumens is still one you should pay attention to as you want to know how much light one lightbulb will emit. Without a sufficient lux level the area that you need the most light in will suffer.

You might be thinking, but which one should I be using when looking for new light bulbs? If you are looking to light a specific area such as a tabletop, work surface or for reading then the figure you need to pay attention to is lux. Lumens is a measure of luminous flux, the total amount of light emitted in all directions. A flux of 1000 lumens, concentrated into an area of one square metre, lights up that square metre with an illuminance of 1000 Lux. It takes into account the area over which the luminous flux (lumens) is spread. Lux is a measure of illuminance, the total amount of light that lands on a surface. In layman's terms, the main difference between these two figures is that lumens is a measurement of how bright a light is going to be, whilst lux tells us where that amount of light output is going to be in a specific area.

For example, with a lamp, lux is usually indicated in the centre of the beam where the intensity of the light is highest. This will give you an indication of what direction the light source shines. This figure allows us to measure the total amount of visible light which is present, and the intensity of the light on a surface. It can be the result of multiple light bulbs and even daylight mixed in. In comparison to lumens, one lux is equal to one lumen per square meter. Lux measures the amount of light output in a singular area. If you would like to read more about colour temperature, visit our blog What is Colour Temperature? for more information. Light colour temperature is unrelated to lumens and lux, however.

Luminous flux to lumens