Phthalo Green vs Medium Grey Blue

How close are they?

ΔE 15.0, fair: the same colour family, but not a straight swap. Medium Grey Blue is noticeably lighter, more muted, warmer than Phthalo Green.

Can I use Medium Grey Blue instead of Phthalo Green?

Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 15). Medium Grey Blue is noticeably lighter, more muted, warmer than Phthalo Green.

Can I use Phthalo Green instead of Medium Grey Blue?

The same difference applies the other way round: Phthalo Green is noticeably 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.