How undertones work — a guide to colours that belong together

Why do some rooms look as though they were made all of a piece, while others never quite "settle" — despite beautiful furniture and costly fabrics? The answer usually lies not in which colours were chosen, but in their undertones. Here we explain what an undertone is, how to spot it and how to use it to make wallpaper, fabrics, rugs and furniture work together.

What is an undertone?

Every colour has an undertone that makes it read as warm, cool or neutral. Warm colours lean towards yellow, red and brown, while cool colours carry hints of blue, grey or violet. Neutral colours sit somewhere in between.

The undertone is rarely the first thing you notice — two beige fabrics can look identical from a distance, yet one leans towards honey (warm) and the other towards stone (cool). Place them side by side and something jars, without anyone quite being able to say why. That is the undertone at odds.

The colour chart: three undertones

For a harmonious overall impression, it is best to stay within one undertone — warm colours with warm, cool with cool. Neutral colours work beautifully as a soft transition between the two.

How to find the undertone

1. Compare against pure white. Hold the fabric or wallpaper sample against a sheet of white paper in daylight. Does the colour lean towards yellow or pink? Warm. Towards blue or grey? Cool.
2. Compare samples with each other. Undertones show best in company — lay two green fabrics side by side and the difference between olive green (warm) and grey-blue-green (cool) becomes clear at once.
3. Look in the right light. Always judge colour in daylight. Warm lighting in the evening makes every colour appear warmer than it is.

The undertone shapes the whole

When you decorate a room, the undertone is your common thread:

• Start with the walls. Choose a wallpaper whose undertone you feel at home with — it sets the tone for everything else.
• Let the textiles follow. Choose fabrics in the same undertone, ideally in varying depths: a light base, a mid-tone and a dark accent give the room depth.
• Use neutrals as a bridge. Chalk white, greige and grey-beige tones tie everything together and give the eye a rest.
• Break the rule deliberately. An accent in the opposite temperature — a rust-coloured cushion in a cool blue-grey room — adds energy. But keep the accent small, or the room loses its direction.

Consider the aspect, too: north-facing rooms receive cool light and often benefit from warm undertones, while south-facing light suits both warm and cool.

Undertones in practice — Brittfurn Colour Match

On our product pages you will find Brittfurn Colour Match — our own colour analysis showing each fabric and wallpaper's main colour, undertone and lightness, together with a colour palette and products selected to work together. The undertone you have just learnt to read is the very engine behind those recommendations.

Frequently asked questions

What is an undertone?

The undertone is the subtle hue that lies beneath a colour's main shade and makes it read as warm, cool or neutral. A beige, for example, may lean towards yellow (warm) or towards grey (cool) — it is the undertone that decides which other colours it sits well with.

How can I tell whether a colour is warm or cool?

Compare it with a reference. Place the fabric or wallpaper sample next to a sheet of pure white paper: if the colour leans towards yellow, red or brown, it is warm; if it leans towards blue, grey or violet, it is cool. The undertone shows most clearly in daylight.

Can I mix warm and cool colours in the same room?

Yes, but do so deliberately and sparingly. Let one undertone dominate and use the other as an accent. Neutral colours are the bridge — they work with both and soften the meeting.

Which undertone suits a north-facing room?

North-facing rooms receive a cool, bluish light. Warm undertones balance it and make the room feel snug, while cool undertones heighten the cool light — handsome if you want a crisp, elegant feel.

What does tone-on-tone mean?

Staying within the same colour family and undertone while varying the lightness — for instance, a pale sage green wallpaper against a deeper olive green fabric. The result is calm and cohesive.