Ultramarine Blue vs Imperial Blue

How close are they?

ΔE 12.3, fair: the same colour family, but not a straight swap. Imperial Blue is more muted, cooler than Ultramarine Blue.

Can I use Imperial Blue instead of Ultramarine Blue?

Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 12). Imperial Blue is more muted, cooler than Ultramarine Blue.

Can I use Ultramarine Blue instead of Imperial Blue?

The same difference applies the other way round: Ultramarine Blue is 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.