Gather Your Ingredients: You'll need rolled oats, also known as old-fashioned oats, to make oat flour.
Measure the Oats: Determine how much oat flour you need for your recipe and measure out the corresponding amount of rolled oats.
Keep in mind that 1 cup of rolled oats will yield approximately 1 cup of oat flour.
Grind the Oats: Place the rolled oats in a high-speed blender or food processor. If you're making a small batch, a coffee grinder can also be used.
Pulse the oats until they are ground into a fine powder-like consistency. You may need to stop and scrape down the sides of the blender or food processor periodically to ensure even grinding.
Sift the Flour (Optional): If you prefer a finer texture, you can sift the oat flour through a fine-mesh sieve to remove any larger pieces of oats that may not have been fully ground.
Store the Oat Flour: Transfer the oat flour to an airtight container or resealable bag for storage. Keep it in a cool, dry place like your pantry or cupboard.