Amazon Sellers Hit by Sudden USPS Shipping Cost Hikes, Lightweight High-Volume Sellers Most Impacted

Recently, foreign media reported that, according to feedback from Amazon US marketplace sellers, their shipping costs using the United States Postal Service (USPS) have experienced a sudden and significant increase.

Official announcements reveal that USPS has completed multiple rounds of rate adjustments in 2026. In January, a general increase of 5.1% to 7.8% was applied to mainstream shipping services. Starting April 26th, a uniform 8% rate hike was implemented across all categories of parcel delivery services (this is a long-term rate change effective until January 2027), covering commonly used seller channels like Priority Mail and Ground Advantage.

The latest rules indicate that USPS will also adjust its parcel dimensional weight pricing rules starting July 12, 2026. This includes rounding up all parcel dimensions to the nearest whole number, lowering the dimensional weight divisor from 166 to 139, and eliminating the per-ounce pricing for Ground Advantage commercial shipments. This means more lightweight, bulky (low-density) packages will be charged based on their dimensional weight, creating potential for further cost increases.

Public information shows that in April 2026, Amazon and USPS signed a new delivery agreement. Under this deal, USPS retains approximately 80% of Amazon's existing parcel delivery volume, handling over 1 billion packages annually, making it one of Amazon's largest last-mile delivery partners. The collaboration focuses on deliveries to rural and remote areas, utilizing a synergistic model combining Amazon's own logistics network with the USPS infrastructure.

The impact of these cost increases affects multiple seller groups, including Amazon sellers using Fulfillment by Merchant (FBM) and those utilizing overseas warehouses for drop-shipping. Among them, sellers specializing in lightweight, low-cost items (with average order values typically in the $10-$30 range) who rely on high sales volume are most directly impacted. For this group, last-mile logistics costs constitute a higher proportion of their expenses, profit margins are relatively thin, and changes in shipping fees have a more pronounced effect on their operations.