Merm Green vs Light Grey RLM63

How close are they?

ΔE 11.5, fair: the same colour family, but not a straight swap. Light Grey RLM63 is a little lighter, more muted than Merm Green.

Can I use Light Grey RLM63 instead of Merm Green?

Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 12). Light Grey RLM63 is a little lighter, more muted than Merm Green.

Can I use Merm Green instead of Light Grey RLM63?

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

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.