ΔE 13.6, fair: the same colour family, but not a straight swap. Light Gray (IJN) is a little lighter, much more muted than Light Feldgrau.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 14). Light Gray (IJN) is a little lighter, much more muted than Light Feldgrau.
The same difference applies the other way round: Light Feldgrau is a little darker, much 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.
See Light Feldgrau on the colour wheel See Light Gray (IJN) on the colour wheel
All matches: Light Feldgrau equivalents · Light Gray (IJN) equivalents