Colour Temperature and Kelvin: how to choose the right light

Colour temperature is one of the most important properties to understand when choosing LED lighting for a business. The right colour temperature creates an environment that feels both pleasant and functional, while the wrong choice can make a room feel cold and uncomfortable or a workplace hard to concentrate in. In this guide we explain what Kelvin and colour temperature really mean, the difference between warm, neutral and cool white, and how to choose the right light for different types of premises.

What is colour temperature?

Colour temperature describes the tone of light and is measured in Kelvin (K). Although it sounds technical, in practice it is simply about how warm or cool the light appears. A low Kelvin value produces a yellowish, warm glow, while a high value produces a bluish, cool light. The term comes from physics: as an object heats up it first glows red and orange, then becomes whiter and bluer at higher temperatures. This is why it can feel counterintuitive that a higher Kelvin value is perceived as a cooler light.

Most LED products for professional use fall between 2700K and 6500K. Here is an overview of how the different ranges are perceived and used.

Warm white, neutral white and cool white

Warm white light (2700K to 3000K) creates a relaxed and inviting atmosphere. It is the first choice in environments where people should feel comfortable and stay a while, such as hotels, restaurants and homes. Neutral white light (3500K to 4500K) appears natural and balanced without being clinical, making it ideal for offices, schools and shops where both comfort and performance matter. Cool white light (5000K to 6500K) delivers high alertness and clear contrast, and is used where precision and safety are the priority, for example in warehouses, industry and outdoor environments.

Which colour temperature suits your space?

Offices and workplaces

For offices, 4000K is usually recommended. The neutral white light keeps staff alert without feeling harsh, and renders colours on screens and paper accurately. In creative spaces or meeting rooms, 3500K can give a slightly softer feel.

Warehouses and industry

In warehouses and production facilities, 5000K is a good choice. The daylight-like light improves visibility on high shelves and in aisles and contributes to safety. Take a look at our high bay lighting for tall ceiling heights.

Retail and showroom

Here the choice depends on what is being sold. Clothing, furniture and food are often best shown at 3000K, while electronics and technology can benefit from 4000K. Good colour rendering is decisive, which we return to below.

Street and outdoor lighting

Outdoors and for street lighting, 4000K to 5700K is commonly used. A neutral to cool light provides good visibility and a sense of security, but in recent years many municipalities have chosen warmer temperatures around 3000K to reduce light pollution and impact on wildlife.

CRI (Ra): colour rendering that matters

Colour temperature only tells you how warm or cool the light is, not how well it renders colours. That is the role of CRI, the Colour Rendering Index, often given as an Ra value on a scale up to 100. A high CRI means colours look natural and accurate under the light.

• Ra 80 to 89: Fully sufficient for most offices, warehouses and general spaces.
• Ra 90 and above: Recommended in shops, showrooms, healthcare and environments where colour accuracy is critical.

Two luminaires with the same colour temperature can therefore give very different results if their CRI differs. When purchasing, you should always consider both Kelvin and Ra value together.

How to choose in practice

Start by considering the function of the space and the feeling you want to create. Then choose the colour temperature according to the table above and make sure the CRI matches your colour rendering requirements. Also think about consistency: do not mix different colour temperatures in the same room, as it quickly looks messy. If you want to calculate the number of luminaires and light output for your area, you can use our lighting calculator. You will find the full range of indoor lighting among our products and specifically among ceiling lights for offices and premises.

The right colour temperature is rarely a matter of right or wrong in absolute terms, but of matching the light to the purpose of the room. With an understanding of Kelvin and CRI, you can make confident decisions that both improve the working environment and lower energy costs.