The dynamic dough density system, which simulates growth during proving of bread dough, was refined to enhance the accuracy and reproducibility of the technique. The system was then used to quantify the expansion capacity of doughs, as indicated by the minimum density achieved by a proving dough piece, in three different scales of geometrically similar laboratory dough mixers. The effects of bran level on dough expansion and baked loaf characteristics were investigated. Dynamic dough density measurements showed no difference in expansion capacity during proving from doughs mixed in the three scales of mixer. Bran at 7.5% flour substitution had no significant effect on the minimum density, but decreased loaf volumes compared with no bran. Addition of bran at 15% substitution decreased loaf volume further and also decreased the maximum expansion during proving, indicating that at this level bran exerts at least part of its effect in reducing loaf volumes during the proving stage of the breadmaking process. Baking scores were comparable for loaves baked from doughs mixed in the two larger scales of mixer, while specific loaf volume decreased as mixer scale decreased.