Methodology

How PaintDial matches colours

PaintDial compares 5,582 paints from nine UK brands and finds the closest matches to any colour — across every brand at once, not just one manufacturer’s range. Here’s exactly how it works, and what its limits are.

Where the colour data comes from

Every colour in the library uses the brand’s own published digital swatch — the colour value each manufacturer provides for its paints on the web. We don’t re-photograph or estimate colours ourselves. LRV (light reflectance value) shown on colour pages is estimated from the swatch rather than measured from paint.

How matches are calculated

Matches are ranked by perceptual colour difference — a measure of how different two colours look to the human eye — computed in the OKLab colour space, which handles hue more faithfully than older formulas (blues stay blue as they lighten, and purples don’t get mistaken for blues). Our ranking also weights hue more heavily than lightness: a paint that’s a touch lighter or darker still reads as the same colour, while one that’s drifted in hue reads as a different colour — so matches keep the colour’s character, and the lighter/darker ladder covers depth.

What the match labels mean

RAL Classic and BS 4800 codes

Trade and specification colours are covered too: type a RAL Classic code (say, “RAL 7016”) or a British Standard BS 4800 code (say, “08 B 15”, Magnolia) — or a colour name — into the tool’s search and PaintDial shows every brand’s nearest paints to it. Our RAL values are derived from the standard’s published CIELAB coordinates; our BS 4800 values are derived from measured colour data (averaged spectrophotometer readings, standardised to D65 / CIE 1964). Both are physical colour standards, so on-screen values are approximate conversions — for binding samples, use an official RAL or British Standard fan deck.

Why photo matching is approximate

The “match from a photo” tool reads the pixel colour from your image. That pixel is shaped by the room’s lighting, the camera’s processing, and your screen — so treat photo matches as a strong starting point, not a guarantee. The same wall photographed at noon and at dusk will match to different paints.

Why you should still order testers

Screen colours are indicative. Real paint changes with sheen, light, and the surface underneath it — and every screen shows colour slightly differently. Before committing to any colour (or any match), order tester pots of both and look at them in the room they’ll live in, in daylight and lamplight.

Found something that looks wrong? Tell us — accuracy is the whole point of PaintDial, and corrections are genuinely welcome.