Phthalo Turquoise Light vs IDF Blue

How close are they?

ΔE 11.2, fair: the same colour family, but not a straight swap. IDF Blue is a little darker, more muted than Phthalo Turquoise Light.

Can I use IDF Blue instead of Phthalo Turquoise Light?

Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 11). IDF Blue is a little darker, more muted than Phthalo Turquoise Light.

Can I use Phthalo Turquoise Light instead of IDF Blue?

The same difference applies the other way round: Phthalo Turquoise Light 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.