Medium Blue vs Signal Blue

How close are they?

ΔE 10.9, fair: the same colour family, but not a straight swap. Signal Blue is a little darker, more muted, warmer than Medium Blue.

Can I use Signal Blue instead of Medium Blue?

Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 11). Signal Blue is a little darker, more muted, warmer than Medium Blue.

Can I use Medium Blue instead of Signal Blue?

The same difference applies the other way round: Medium Blue is a little lighter, more saturated, cooler.

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.