A 100 g serving of commercial US apple pie has about 237 kilocalories.
The figure comes from the nutrition data for commercially prepared apple pie made with enriched flour. The same serving provides about 992 kilojoules, reflecting the energy supplied mainly by its pastry, sugar, and fat.
This is a standardized 100 g reference amount, not necessarily the calorie count of a typical slice. Slice sizes vary considerably, and homemade pies can differ because of their crust thickness, sugar level, butter or shortening, and filling. Adding ice cream, whipped cream, or custard raises the total further.
The number is also easy to confuse with the calories in a plain apple. Raw apples are much less energy-dense because they contain more water and no pastry or concentrated added sugar. Apple pie’s fruit filling contributes flavor and some fiber, but the crust and sweeteners account for much of its energy.