ΔE 14.0, fair: the same colour family, but not a straight swap. Medium Blue is a little darker, more muted, cooler than Indigo Sky.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 14). Medium Blue is a little darker, more muted, cooler than Indigo Sky.
The same difference applies the other way round: Indigo Sky is a little lighter, 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.
See Indigo Sky on the colour wheel See Medium Blue on the colour wheel
All matches: Indigo Sky equivalents · Medium Blue equivalents