Hi Erin, it’s usually not a 1:1 sub, it can really affect the rise of baked goods. In the post text, we’ve listed lots of recipes that have been well tested to incorporate oat flour so I’d maybe start with those.

What would be the substitute ratio of oat flour to all purpose flour ?

Hi Hilary, I haven’t tried it but I’m not sure if it would get fine enough in a regular food processor. If you have a vitamix with a dry container, I think that might work.

Quick or instant oats are sometimes pre-cooked. Their flour might act differently when baking.