When colour contrast is worth the effort

This is cheap to get right at the start and expensive to retrofit. Colour contrast is not free, and pretending otherwise leads to bad decisions.

The measurable part of design is whether people can find what they came for and act on it without hesitating. Check it against what you would want a competitor's site to get wrong.

When it is worth it

Body text needs a 4.5:1 contrast ratio against its background. Small and consistent beats large and occasional here. The teams that stay on top of it are the ones who put it on a calendar rather than a wish list.

When it is not

If nothing downstream depends on it and nobody is complaining, it can wait. Getting it slightly wrong is survivable. Ignoring it entirely is not.

How to decide

Contrast checkers take seconds and settle arguments. In practice this is a scheduling problem more than a technical one. Write the reasoning down alongside the decision, because the reasoning is what changes first.

The short version

Consistency is the quiet half of design work: it rarely gets complimented, and its absence is noticed immediately. Three things worth confirming about colour contrast before you move on:

• Someone can say what the current setup is without going to look
• Contrast checkers take seconds and settle arguments — and you know whether that is true here
• There is a way to tell whether the last change to this helped

Pick the one that would hurt most if it failed, and start there.