The barrel fold is a common fold that reveals more information as the piece is unfolded (see right figure). Barrel folds are often used in brochures.
The outer two panels of barrel folds should be final size: the dimensions the end product will be.
Each succeeding interior panel should decrease in width at a constant rate. The last panel should be smaller than the preceding one. Plan for the thickness of your paper, accommodating for the weight to ensure your folds end up where you want them. For text weight stock, reduce each succeeding interior panel by 1/16". For cover weight, reduce by 3/32".