ΔE 15.0, fair: the same colour family, but not a straight swap. Ivory is a little darker, much more saturated than Zinc White.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 15). Ivory is a little darker, much more saturated than Zinc White.
The same difference applies the other way round: Zinc White is a little lighter, much more muted.
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 Zinc White on the colour wheel See Ivory on the colour wheel
All matches: Zinc White equivalents · Ivory equivalents