Ultramar Blue vs French Blue

How close are they?

ΔE 10.4, fair: the same colour family, but not a straight swap. French Blue is a little lighter, more muted, cooler than Ultramar Blue.

Can I use French Blue instead of Ultramar Blue?

Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 10). French Blue is a little lighter, more muted, cooler than Ultramar Blue.

Can I use Ultramar Blue instead of French Blue?

The same difference applies the other way round: Ultramar Blue is a little darker, more saturated, warmer.

ΔE is the colour difference between our two swatch estimates: under about 6 is close, over about 15 is loose. Real paints also differ in finish, coverage and how they thin, so test before you commit.