ΔE 10.5, fair: the same colour family, but not a straight swap. Light Red is a little lighter than Naphthol Red Medium.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 10). Light Red is a little lighter than Naphthol Red Medium.
The same difference applies the other way round: Naphthol Red Medium is a little darker.
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.
See Naphthol Red Medium on the colour wheel See Light Red on the colour wheel
All matches: Naphthol Red Medium equivalents · Light Red equivalents