ΔE 14.9, fair: the same colour family, but not a straight swap. Grey Blue is much more muted, warmer than Tidal Blue.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 15). Grey Blue is much more muted, warmer than Tidal Blue.
The same difference applies the other way round: Tidal Blue is much 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.
See Tidal Blue on the colour wheel See Grey Blue on the colour wheel
All matches: Tidal Blue equivalents · Grey Blue equivalents