---
name: sRGB
slug: srgb
category: color
status: published
created: 2026-08-21T00:00:00.000Z
modified: 2026-08-26T00:00:00.000Z
definition: The default colour space of the web, the one hex codes and plain
  rgb() values live in, and the baseline every wider gamut is described relative
  to.
aliases:
  - name: standard RGB
  - name: RGB
    source: community
  - name: web-safe color space
    source: community
tags:
  - perception
  - web-platform
relations:
  contrastWith:
    - wide-gamut
    - color-space
    - cmyk
    - hex-color
    - additive-color
  variantOf: []
  partOf: []
  seeAlso: []
implementations: []
sources:
  - title: CSS Color Module Level 4
    url: https://www.w3.org/TR/css-color-4/
  - title: "MDN: <color> CSS type"
    url: https://developer.mozilla.org/en-US/docs/Web/CSS/Reference/Values/color_value
demo: inline
exhibit: false
useWhen: the assumed colour space behind a hex code
---

sRGB was written in 1996 by Hewlett-Packard and Microsoft to describe the screen almost
everyone already had: a CRT monitor in a dim office. It pins three primaries, a D65 white
point, and a transfer curve, and that is the whole of it. Because it described the average
device rather than an ideal one, it became the value everything defaulted to, and thirty
years later it still is. An untagged `#1D63D2` in a stylesheet, an untagged JPEG, a colour
picked in a design tool with no profile set: all of them mean sRGB, and none of them say so.

The web writes it three ways and they are the same space. `#E5342B`, `rgb(229 52 43)` and
`color(srgb 0.898 0.204 0.169)` name one colour; only the notation differs, hex and `rgb()`
counting in 0 to 255 and the `color()` form in 0 to 1. What none of the three are is linear
light. sRGB channel values carry a transfer curve of roughly the 2.2 power, which is why
you cannot average two hex codes and get the colour halfway between them, and why every
[contrast ratio](/contrast-ratio) starts by undoing that curve to recover
[relative luminance](/relative-luminance).

It is a small space. As a [colour gamut](/color-gamut) it covers about a third of what a
person can see, and its reddest red is noticeably duller than a modern laptop can actually
produce. Reaching past it is now a one-line decision: `color(display-p3 1 0 0)` asks for a
red outside the sRGB triangle, and `oklch()` will accept a chroma beyond any display at
all. The discipline is to spend the extra range on decoration and keep anything load
bearing inside sRGB, because a browser that cannot show the wider value maps it back in and
two screens then disagree about what you wrote.

Two naming confusions are worth clearing. First, "RGB" on its own is a
[colour model](/color-space), a set of axes with no fixed meaning, while sRGB is that model
with its numbers pinned to actual light, which is why the same triple names a different
colour in Display P3. Second, the old "web-safe" palette is not this: that was the 216
colours a 256-colour graphics card could show without dithering in the late nineties, a
constraint that died with the hardware. sRGB is not a restricted palette. It is the space
the rest of the stack assumes when nobody says otherwise.