A short guide to colour contrast

There is no clever trick in this one, just a handful of decisions worth making deliberately. Everything we would tell a client about colour contrast in the time it takes to drink a coffee.

Consistency is the quiet half of design work: it rarely gets complimented, and its absence is noticed immediately. Most teams find the first pass takes an afternoon and the maintenance takes minutes a month.

What it costs to ignore

Body text needs a 4.5:1 contrast ratio against its background. The teams that handle this well are rarely the ones with the biggest budgets. The failure mode is not doing it wrong, it is doing it once and assuming it stays done.

The practical version

Light grey on white fails more often than designers expect. That sounds obvious written down. It is still the thing most often skipped. It is the sort of thing that looks like polish right up until it costs you an enquiry.

What to watch for

Contrast checkers take seconds and settle arguments. It is worth being explicit about, because assumptions differ quietly. Doing this properly once is usually cheaper than doing it approximately three times.

How to tell if yours is fine

The measurable part of design is whether people can find what they came for and act on it without hesitating. Three things worth confirming about colour contrast before you move on:

• Someone can say what the current setup is without going to look
• Body text needs a 4.5:1 contrast ratio against its background — and you know whether that is true here
• There is a way to tell whether the last change to this helped

The point is not perfection, it is knowing which of these you have consciously chosen to skip.