---
name: Color temperature
slug: color-temperature
category: color
status: published
created: 2026-08-21T00:00:00.000Z
modified: 2026-08-21T00:00:00.000Z
definition: Whether a colour reads warm (toward red and orange) or cool (toward
  blue), the axis designers use to bias a neutral grey without changing its
  lightness.
aliases:
  - name: warm and cool colors
    source: community
  - name: warm grey
    source: community
  - name: cool grey
    source: community
  - name: warm gray
    source: community
  - name: cool gray
    source: community
tags:
  - perception
relations:
  contrastWith:
    - tint
    - hue-shift
    - tinted-neutral
  variantOf: []
  partOf: []
  seeAlso:
    - hue
implementations: []
sources:
  - title: "Design Glossary: Basic Color Terminology"
    url: https://design4users.com/basic-color-terminology/
demo: inline
exhibit: false
useWhen: biasing a palette warm or cool
---

Temperature splits the wheel in half: reds, oranges and yellows are warm, blues and
cyans are cool, with green and magenta sitting on the fence and going either way depending
on which side of themselves they lean. The vocabulary comes from the colour of hot metal
and from photography's Kelvin scale, which is why the physics reads backwards here. A
higher colour temperature in Kelvin is a bluer light, so the number goes up as designers
would say the colour gets cooler.

The everyday use of the word is not about colourful things at all, it is about greys. A
neutral at zero [saturation](/saturation) is inert and slightly dead, so most systems keep a
few percent of a hue in theirs: a warm grey holds a trace of yellow or red and reads like
paper and daylight, a cool grey holds a trace of blue and reads like screens, steel and
clinical spaces. The trick is that the bias changes only the hue, never the
[lightness](/lightness), so a warm and a cool version of the same step are equally light and
the interface's contrast ratios do not move when a team switches from one to the other.

Getting the bias to agree across a palette is the actual craft. Warm greys under a cool blue
accent make the accent look slightly dirty, and a single cool border in an otherwise warm
panel reads as a mistake nobody can name. Pick a direction, apply it to every neutral, and
choose accents that lean the same way. Readers meet the same axis at the system level too,
where Night Shift, f.lux and "warm" display modes shift the whole white point toward amber
after dark, which is worth remembering when a carefully cooled interface is being viewed
through an orange filter.

Two limits. Temperature is relative rather than absolute, so a warm blue and a cool red are
both perfectly ordinary things to say, and a colour only reads as warm next to something
cooler. And it carries no contrast of its own: shifting a grey warm does nothing for
legibility, which stays a question of how far apart two colours sit on the lightness axis.