Blue Horror vs Underbelly Blue

How close are they?

ΔE 12.7, fair: the same colour family, but not a straight swap. Underbelly Blue is a little lighter, more muted than Blue Horror.

Can I use Underbelly Blue instead of Blue Horror?

Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 13). Underbelly Blue is a little lighter, more muted than Blue Horror.

Can I use Blue Horror instead of Underbelly Blue?

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

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.