Shape changes how cereal pours, absorbs liquid and fills the bowl. It can also make two equal-weight servings look very different.
Puffed and crisped cereals
Heat and pressure can expand grains or grain doughs into light pieces. These cereals may be very light by volume, so a large-looking bowl is not necessarily a large weight.
Flaked cereals
Grains or cooked grain mixtures are rolled or formed into flakes and toasted. Thickness and coating affect how quickly they soften.
Shredded cereals
Cooked grains are formed into strands or layers. The resulting biscuits or pieces are comparatively dense and often remain structured in liquid.
Compare by the same weight
When one cereal is airy and another is dense, cup measures create confusion. Compare per 100 g or use matching gram weights, then decide which texture and portion appearance you prefer.