Colour temperature, measured in Kelvin (K), represents the visual appearance of a light bulb. The higher the Kelvin rating given to the light bulb, the cooler its appearance will be.

• 6500K – Natural Daylight (how the sun appears at midday)
• 5000K - Daylight
• 4000K – Cool White
• 3500K – White
• 3000K – Warm White
• 2800K – Very Warm White

To make your life easier we have tried to include the colour temperature of the lamp in either the lamps name or SKU.

If the lamp does not state the colour temperature in kelvin then look out for a 3 digit code.

The code is split into two parts, the first digit represents the CRI of the lamp, and the second and third digits represent the colour temperature in hundreds of Kalvin.

Let’s take the product ‘F58W/835 T8’ as an example. Here the 835 means that this lamp has a CRI in the 80s and a colour temperature of 3500K.

Lamp types and their colour temperature

Most incandescent bulbs have a colour temperature of 2700K.

Halogen bulbs normally have a colour temperature of 3000K.

Compact fluorescent lamps and fluorescent tubes are available in a variety of temperatures but typically come in 3500K.

LED bulbs are available in a full range of colour temperatures. LED technology had previously struggled with producing the low temperature very warm whites but this is not the case now with current LEDs.

Choosing the correct colour temperature

The colour temperature of the lamps you use will have a significant impact on the look and feel of any objects in a room. The colour walls are painted could appear different and furniture or decorations can go from popping with colour to looking dull.

Additionally a room’s ability to fulfil its purpose could also be dramatically altered with an incorrect colour temperature. Is the room for relaxing in or for completing complicated work in? Recently studies have been conducted to show how reading and concentration improves in school classrooms when they use daylight 5000K+ lamps.

Saltwater aquariums use very high colour temperature lamps to provide essential energy for algae and coral. Lamps for aquariums can range as high as 20k.

The colour temperature of lamps

The colour temperature is just one of many different attributes that make up a lamp's specification. To find out more about the different attributes and the information listed against each lamp we’ve create a guide to light bulb terminology explaining what each feature means.