Paint doesn't have a fixed colour — it reflects whatever light hits it. Change the light, change the colour. And LEDs are the worst offenders because their light isn't a smooth spectrum like daylight or old incandescent bulbs; it's spiky, with gaps in certain wavelengths. That's why a colour you chose under the showroom halogens can look completely wrong once your downlights go in.
The number that matters is colour temperature, measured in Kelvin:
- 2700K (warm white) — the closest to the old tungsten bulbs. Flatters reds, pinks, terracottas and warm neutrals. Makes cool greys look better balanced.
- 3000K (soft white) — slightly crisper, good all-rounder for kitchens and bathrooms.
- 4000K+ (cool white / daylight) — pushes everything blue. Makes warm whites look grey and tired, and can turn a lovely greige cold and clinical.
So a colour like Farrow & Ball Setting Plaster sings under 2700K — its pink warmth comes alive. Stick it under 4000K downlights and it flattens into something muddier. Same with Little Greene Joanna or any complex warm neutral. Conversely, a cool blue like Farrow & Ball Inchyra Blue holds up better under cooler light, where warm bulbs can make it look slightly green.
The other thing nobody mentions: CRI (Colour Rendering Index). Cheap LEDs sit around CRI 80, which means colours look washed out and slightly off. Spend on CRI 90+ bulbs and your paint will look the way the colour card promised. This matters more than the brand of paint, honestly.
Practical advice: decide your bulbs before you commit to a colour, not after. Get your sample pots up on the wall and view them under the actual fittings you'll be living with, at night, not just in daylight. And for most homes, 2700K at CRI 90+ is the safe bet — it keeps warm colours warm and stops cool colours going clinical. Get that sorted and half your colour grief disappears.