Colour Difference Calculator

Two colours forty steps apart in RGB can look nearly identical or obviously different depending on where in the range they sit, because RGB is not perceptually uniform. Delta E measures the difference in a space built to match how we actually see, where equal numbers mean roughly equal perceived differences. This computes both figures and shows how far apart they are.

First colour red

0 to 255, as in a hex colour's first pair of digits.

First colour green

0 to 255. Green dominates perceived brightness.

First colour blue

0 to 255. Blue contributes least to brightness.

Second colour red

The red channel of the colour being compared.

Second colour green

The green channel of the colour being compared.

Second colour blue

The blue channel of the colour being compared.

Your result will appear here.

What this generator does

Converts both colours through linear RGB and XYZ into Lab, then measures the straight-line distance between them there. It also computes the plain RGB distance so the two can be compared, and checks the metric's own properties before display.

How to use this tool

Enter the red, green and blue values of both colours.
Read the Delta E and what it means in practice.
Compare it against the plain RGB distance underneath.
Try two dark colours and two light ones with the same RGB gap.

Understanding the controls

Both colours' channels: Red, green and blue from 0 to 255 for each colour — six fields, the same numbers a hex code encodes. Worth trying with them: a step of forty on every channel measures a Delta E of about 18 between two dark greys (10 and 50) and about 14 between two light ones (200 and 240), while the RGB distance is 69.28 for both.

Common use cases

Checking whether two brand colours are close enough to substitute
Setting a tolerance for colour reproduction
Teaching why RGB distance is a poor measure of perceived difference
Comparing a colour against its nearest match in a palette
Measuring how far a rendered colour has drifted from a specification

How this generator works

RGB values are first linearised, undoing the gamma curve displays apply, then converted to XYZ and on into Lab — a space designed so that equal distances correspond roughly to equal perceived differences. Delta E is the straight-line distance in Lab. Before display the measure is checked against the properties any distance must have: symmetric between the two colours, zero when and only when the colours are identical, and never negative. The figure is also worked a second time by a separate conversion written from the sRGB and CIE standards, and the two must agree to the hundredth shown. The words beside it — indistinguishable below 1, just noticeable below 2.3, related below 10, plainly different below 49 — go with the figure as printed, so a difference shown as 2.3 is never described as under 2.3.

Randomness and fairness

Nothing here is random. Two colours give exactly one difference.

For how randomness is produced across the whole site, see how Generate Random works.

Limitations and good to know

This is the original 1976 Delta E, which is simple and known to overstate differences in saturated blues; the 2000 revision corrects that at the cost of a much longer formula.
Colours are assumed to be sRGB with a standard white point, so a wide-gamut colour will not convert correctly.
Perceived difference also depends on size, surround and lighting, none of which a number can capture.
The thresholds quoted are conventions from print and display practice, not hard boundaries.

Privacy and your data

Both colours are compared in your browser and nothing you enter is transmitted, stored or included in analytics.