Pixie Pink vs Light Magenta

How close are they?

ΔE 24.3, loose: different enough that you should pick on purpose. Light Magenta is noticeably lighter, much more muted, warmer than Pixie Pink.

Can I use Light Magenta instead of Pixie Pink?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 24). Light Magenta is noticeably lighter, much more muted, warmer than Pixie Pink.

Can I use Pixie Pink instead of Light Magenta?

The same difference applies the other way round: Pixie Pink is noticeably darker, much 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.