What is dimensional weight and how does it affect costs?

Dimensional weight (DIM weight) is a pricing method based on package volume rather than actual weight. Carriers charge whichever is greater: actual weight or DIM weight. Formula: L×W×H ÷ DIM factor (typically 5000 for cm or 139 for inches). Large, lightweight items are most affected. Smart packaging that minimises box size directly reduces DIM weight and shipping costs.