Overview

Amazon's Optimized Seller-Set Transit (OST) is a shipping feature designed to help seller-fulfilled merchants offer faster and more accurate delivery estimates on standard shipping orders. Rather than relying on static transit time settings, OST uses real historical carrier data to dynamically calculate delivery windows based on the distance between your warehouse and each customer's location. This feature is currently available on an invitation-only basis.

Key Points / What Sellers Need to Know

• Dynamic transit time calculations — OST replaces manual transit time estimates with data-driven calculations based on actual carrier shipping performance between your warehouse and the buyer's location.
• Standard shipping only — The feature applies exclusively to seller-fulfilled standard shipping settings and cannot be used for expedited or other shipping methods.
• Invitation-only access — OST is not yet available to all sellers. Amazon is rolling it out gradually through direct invitations.
• Default address matters — The feature relies on your default shipping warehouse address to calculate transit times, so keeping this information accurate and current is essential.
• No conflict with SSA — If you already use Shipping Settings Automation (SSA) on a template, you do not need to separately enable OST on that same template.

How It Works

OST pulls from historical shipping data collected across Amazon's carrier network to estimate how long a package will realistically take to travel from your default ship-from location to a given customer's address. Instead of you manually setting transit times that may be overly conservative or inaccurate, the system adjusts delivery promises dynamically for each order. This means customers in nearby regions may see faster delivery estimates, while those farther away receive appropriately adjusted windows. The result is a delivery promise that more closely reflects actual shipping performance, reducing both late deliveries and unnecessarily padded timelines.

How to Enable OST

To turn on Optimized Seller-Set Transit, navigate to your Shipping Settings page within Seller Central. From there, go to the Shipping Templates section. For an existing template, click to edit the template and scroll down until you find the "Optimized seller-set transit" toggle, then switch it on. If you are creating a new shipping template, the same toggle will appear during the setup process. After making your selection, save your changes to apply them. The process takes just a few clicks, and you can enable or disable it at any time without contacting Amazon support.