ΔE 16.5, loose: different enough that you should pick on purpose. IAF Sand is a little lighter, much more muted, cooler than Pure Filth.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 17). IAF Sand is a little lighter, much more muted, cooler than Pure Filth.
The same difference applies the other way round: Pure Filth is a little darker, much more saturated, warmer.
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 Pure Filth on the colour wheel See IAF Sand on the colour wheel
All matches: Pure Filth equivalents · IAF Sand equivalents