Inner Light vs Flat Yellow

How close are they?

ΔE 12.5, fair: the same colour family, but not a straight swap. Flat Yellow is a little darker, more saturated than Inner Light.

Can I use Flat Yellow instead of Inner Light?

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

Can I use Inner Light instead of Flat Yellow?

The same difference applies the other way round: Inner Light is a little lighter, more muted.

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.