Elven Green vs Bile Green

How close are they?

ΔE 54.6, loose: different enough that you should pick on purpose. Bile Green is noticeably lighter, much more saturated, warmer than Elven Green.

Can I use Bile Green instead of Elven Green?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 55). Bile Green is noticeably lighter, much more saturated, warmer than Elven Green.

Can I use Elven Green instead of Bile Green?

The same difference applies the other way round: Elven Green is noticeably darker, much more muted, 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.