USPS Shipping Rates Calculator
USPS shipping rates respond directly to package weight, dimensional weight, destination zone and postal class. The retail base rate stays steady for each class, while the per-ounce rate, zone surcharge and fuel adjustment reflect operational costs for parcels moving through the network.
Dimensional weight is calculated in ounces by dividing the interior volume (length × width × height) by 166. This calculator compares real weight and dimensional weight, then applies USPS mail-class pricing tiers—Priority Mail, Priority Mail Express, First-Class Package Service and Retail Ground—so you can see how different choices affect your final retail charge.
The destination zone (1–8) is based on the distance between the origin and recipient ZIP codes. Each zone mixes with the billable weight to add a per-ounce zone surcharge, mimicking how USPS charges more for longer hauls.
Example
Shipping a 14-ounce hardcover textbook measuring 9″ × 6″ × 1.5″ to Zone 4 via Priority Mail typically yields a billable weight of 14 oz, a modest zone surcharge and a final retail rate around $11.45 plus the 6.5% fuel surcharge embedded in the calculator output.