Thunderous Blue vs Caspian Blue

How close are they?

ΔE 11.6, fair: the same colour family, but not a straight swap. Caspian Blue is a little lighter, more muted, cooler than Thunderous Blue.

Can I use Caspian Blue instead of Thunderous Blue?

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

Can I use Thunderous Blue instead of Caspian Blue?

The same difference applies the other way round: Thunderous 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.