---
title: "What drives USPS shipping rates the most?"
url: "https://www.shipstation.com/faq/what-drives-usps-shipping-rates-the-most/"
type: "faq"
modified: "2026-06-10T09:37:02-05:00"
---
Weight, dimensions, distance, and service speed have the biggest impact. That’s why an accurate USPS shipping cost breakdown starts with precise package details and the right package type.