Convert ingredient proportions from the original recipe to fit your own baking pan. Add ingredients and provide dimensions to check how much you need.
Your pan is the same size
A 9-inch round pan actually holds about 25% more batter than an 8-inch round pan. If you don't scale the ingredients up, your cake layers will be significantly thinner and will bake (and potentially dry out) much faster.
Always measure baking pans across the top from the inside edge to the inside edge. Do not include the outer rim or handles in your measurements.