ΔE 10.6, fair: the same colour family, but not a straight swap. Primary Blue is a little lighter, cooler than Ionic Blue.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 11). Primary Blue is a little lighter, cooler than Ionic Blue.
The same difference applies the other way round: Ionic Blue is a little darker, 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.
See Ionic Blue on the colour wheel See Primary Blue on the colour wheel
All matches: Ionic Blue equivalents · Primary Blue equivalents