Primary Yellow vs Lemon Yellow

How close are they?

ΔE 11.6, fair: the same colour family, but not a straight swap. Lemon Yellow is a little darker, more muted than Primary Yellow.

Can I use Lemon Yellow instead of Primary Yellow?

Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 12). Lemon Yellow is a little darker, more muted than Primary Yellow.

Can I use Primary Yellow instead of Lemon Yellow?

The same difference applies the other way round: Primary Yellow is a little lighter, 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.