Because of its absorptive properties, tapioca flour is often used as a thickening agent in recipes. Made from the cassava tuber, and sweeter than rice flour, tapioca flour is best substituted for rice flour in recipes such as pancakes, pie filings and pastries. When using tapioca flour instead of rice flour do not make the mistake of using plain tapioca, which has a grainier texture than tapioca flour.
Determine how much rice flour the original recipe calls for.
Substitute twice the amount of tapioca flour for rice flour. For example, if the recipe calls for 1/2 cup of rice flour replace it with 1 cup of tapioca flour.
Modify the substitution for recipes that have flour as the main ingredient - using large qualities of tapioca flour as the main ingredient can result in the finished baked goods being overly dense. For example, if you are working with a bread recipe calling for 2 cups of rice flour use 1 cup rice flour and 1 cup tapioca flour. However, since you need to double the amount when substituting tapioca flour you would need to use 2 cups of tapioca flour along with 1 cup of rice flour.