ΔE 13.5, fair: the same colour family, but not a straight swap. Royal Blue is a little darker, more muted than Calth Blue Clear.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 13). Royal Blue is a little darker, more muted than Calth Blue Clear.
The same difference applies the other way round: Calth Blue Clear is a little lighter, 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.
See Calth Blue Clear on the colour wheel See Royal Blue on the colour wheel
All matches: Calth Blue Clear equivalents · Royal Blue equivalents