Place the raw coriander seeds in a spice grinder. Grind for about 1 minute, stopping and shaking the grinder as needed to help evenly distribute the spices. The seeds will grind to a fine, textured powder.
Transfer the ground coriander (use a spice funnel to make this easier) to a spice jar or a small airtight container. Store for up to 6 months. (See Storage Tips.)
Note 1: In most cases, I use raw coriander seeds to make coriander powder. See post for tips on when it's best to toast and how to toast before grinding.Note 2: The coriander powder will remain same weight after grinding but will be less in volume (cups). (3/4 cup coriander seeds = ~2/3 cup coriander powder).