Updated June 17, 2026
Compare carrier rates for your package
Enter weight and dimensions for side-by-side ballpark rates from USPS, UPS, and FedEx.
The formula every major carrier uses: Cost = Billable Weight x Rate per pound for the applicable zone. Billable weight is the higher of actual weight or dimensional (DIM) weight. Zones are assigned based on the distance between origin and destination ZIP codes. Higher zones mean longer distances and higher rates. It is not complicated. It just takes a moment to notice that your box is being weighed twice.
Step-by-step calculation
- Find the actual weight. Weigh the packaged item in pounds. Round up to the next whole pound (or half-pound for some USPS classes).
- Calculate DIM weight. (L x W x H in inches) / DIM divisor. UPS and FedEx use 139; USPS uses 166 for packages over one cubic foot. Example: a 12x10x8 box = 960 cubic inches / 139 = 6.9 lbs DIM weight.
- Take the higher of the two. If actual weight is 4 lbs but DIM weight is 6.9 lbs, you pay for 7 lbs.
- Find your zone. Enter origin and destination ZIP codes on the carrier's zone chart or website.
- Look up the rate. Apply the carrier's published or contracted rate for that weight and zone combination.
Why rates differ by carrier
USPS, UPS, and FedEx each have different base rate structures, zone maps, and DIM divisors. USPS Priority Mail flat rate options ignore weight entirely for boxes that fit and close. UPS and FedEx Ground are often competitive for heavier packages going to nearby zones. USPS tends to be cheapest for lightweight packages going anywhere.
Surcharges to account for
Published rates are base rates. Most carriers add residential delivery surcharges, fuel surcharges (which change weekly), and additional handling fees for oversized packages. The final invoice often runs 15 to 30 percent above the base rate for residential ground deliveries. That gap between "quoted" and "billed" is where a lot of shipping budgets quietly evaporate.
Compare carrier rates for your package
Enter weight and dimensions for side-by-side ballpark rates from USPS, UPS, and FedEx.