ΔE 11.2, fair: the same colour family, but not a straight swap. Pale Olive is a little darker, more saturated, cooler than Underhive Ash.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 11). Pale Olive is a little darker, more saturated, cooler than Underhive Ash.
The same difference applies the other way round: Underhive Ash is a little lighter, more muted, 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 Underhive Ash on the colour wheel See Pale Olive on the colour wheel
All matches: Underhive Ash equivalents · Pale Olive equivalents