ΔE 10.4, fair: the same colour family, but not a straight swap. Ink Blue is more muted than Macragge Blue. They are different kinds of paint: Citadel Macragge Blue is an opaque base/layer paint and Vallejo Ink Blue is an ink, glaze or transparent paint, so they won’t behave the same on the model even where the colour is close.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 10). Ink Blue is more muted than Macragge Blue. They are different kinds of paint.
The same difference applies the other way round: Macragge Blue is 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 Macragge Blue on the colour wheel See Ink Blue on the colour wheel
All matches: Macragge Blue equivalents · Ink Blue equivalents