Fill your food processor or blender between 1/4 and 1/2 full of oats.
Begin grinding the oats and continue until they turn into a fine powder.
If necessary, scrape down the sides of your food processor or blender every so often.
You can use your oat flour right away or store in an airtight container for later.
Notes
The amount of oat flour you have at the end of the process will always be slightly less than the amount of oats you started with. Always measure oat flour before using it in a recipe.