Dimensional weight, zones, carrier differences and savings.
Carrier rates for the same package can differ by 30 percent or more. What follows is what drives that gap, and where the money goes.
Carrier rates depend on weight, size, distance (zone) and speed. The Shipping Rate Estimator compares rates side by side so you can see the cheapest option for a given package and destination. For most parcels, the cost surprise comes from size, not weight. (A shoebox of foam peanuts will teach you this faster than any guide.)
Carriers bill the greater of actual weight and dimensional (DIM) weight, which converts a package's volume into a billable weight. A big, light box can cost far more than its scale weight suggests. The Dimensional Weight calculator shows the DIM weight before you ship, which is also why right-sizing the box saves money.
Shipping zones measure distance from origin to destination; higher zones cost more. Speed multiplies that cost. Overnight and two-day rates run far above ground. Choosing ground when timing allows, and shipping from a location closer to customers, both cut zone-driven charges.
USPS often wins on small, light packages; UPS and FedEx are competitive for heavier or larger parcels and offer deeper business discounts. Regional carriers can beat all three on certain lanes. No carrier wins every shipment, so comparing per package is where the actual savings are.
Right-size packaging to reduce DIM weight, compare carriers per shipment, use flat-rate options for dense items, negotiate volume discounts, and buy postage online rather than at the counter. Consolidating shipments and placing inventory closer to the customer both reduce zone charges.
Weight, package size, distance (zone) and speed.
A billable weight derived from a package's volume; carriers charge whichever is higher, DIM weight or actual weight.
Distance bands from origin to destination - higher zones cost more.
USPS often wins on small light parcels; UPS and FedEx on heavier ones. Compare per package.
Right-size boxes, compare carriers, use flat-rate for dense items, and negotiate volume discounts.