Pestilence Green vs Ice Yellow

How close are they?

ΔE 17.3, loose: different enough that you should pick on purpose. Ice Yellow is a little lighter, more muted, warmer than Pestilence Green.

Can I use Ice Yellow instead of Pestilence Green?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 17). Ice Yellow is a little lighter, more muted, warmer than Pestilence Green.

Can I use Pestilence Green instead of Ice Yellow?

The same difference applies the other way round: Pestilence Green is a little darker, 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.