---
title: How to configure your preferred carriers in ShipStation
description: Learn how to assign a carrier to an order and how to configure automation rules to automatically assign your preferred carrier(s) based on order properties
---

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# How to configure your preferred carriers in ShipStation

## Learn how to assign a carrier to an order and how to configure automation rules to automatically assign your preferred carrier(s) based on order properties

### Assigning a carrier to an order

Every order needs a carrier assigned to it for shipping.  In ShipStation, there are two ways to assign a carrier to an order:

- Select a carrier/service directly in ShipStation from the available carriers in the "Configure Shipment" section of an order,   
  ![](https://help.shipcalm.com/hs-fs/hubfs/image-png-Feb-17-2025-07-50-09-0110-PM.png?width=309&height=446&name=image-png-Feb-17-2025-07-50-09-0110-PM.png)
- Or simply add a Tag to the order that specifies which carrier to use.  
  ![](https://help.shipcalm.com/hs-fs/hubfs/image-png-Feb-17-2025-07-51-12-8064-PM.png?width=458&height=284&name=image-png-Feb-17-2025-07-51-12-8064-PM.png)

Important notes:

- Ideally only one of these methods is used, but if it so happens that an order has both a selected carrier and a carrier tag, then the selected carrier takes precedence.
- If more than one carrier tag is added to an order, then no carrier will be selected because the system cannot determine which carrier is preferred.
- If your desired carrier does not already exist in the list of available order tags, then please contact ShipCalm Support to add the missing carrier tag.
- If you are unsure of which carrier to choose, we recommend using Marvin Shops™ to rate shop across all of our available our carriers and automatically select the best option for you ([see below](https://help.shipcalm.com/en/knowledge-base/how-to-set-a-carrier-in-shipstation#Marvin-Shops)).

### Automatically assigning carriers using automation rules

ShipStation automation rules can be configured to automatically assign a carrier or a carrier tag to orders as they import.  Automation rules can be configured based on a large variety of order specific properties and are capable of performing many actions once an order is matched against the properties specified.  For a general introduction to automation rules, please refer to [ShipStation's Guide](https://help.shipstation.com/hc/en-us/articles/360047475591-Introduction-to-Automation-Rules). 

For assigning carriers, it is most common to use either the "Requested Service (Marketplace Value)" field or a "Custom Field" that contains tags set by the shopping cart or originating order source.  For example, the following automation rule sets a specific carrier whenever the requested shipping service is "Free Shipping":

![](https://help.shipcalm.com/hs-fs/hubfs/image-png-Feb-17-2025-08-23-39-0532-PM.png?width=670&height=516&name=image-png-Feb-17-2025-08-23-39-0532-PM.png)

For additional support or to request a review of your automation rules, please contact ShipCalm Support.

### Leveraging Marvin Shops™ for the best rates

Often the best choice is to not select a specific carrier at all, but instead let ShipCalm's helpful robot Marvin make a selection for you after rate shopping an order across all our available carrier options. To take advantage of Marvin Shops™ you must ensure that

- all SKUs in Infoplus have accurate length, width, height and weight recorded in the Item table, and
- your desired packaging has been reviewed and configured.

These data are required for Marvin to retrieve accurate freight quotes.  Once these data are verified, we can configure Marvin Shops™ to find the cheapest shipping costs subject to maximum transit time constraints like "use the cheapest carrier/service available that will still deliver this package within 3 days."  If you are interesting in leveraging Marvin Shops™ then please review your SKU data and ask your ShipCalm Head of Ops to assist you with the configuration.

### Rate Shop Carrier Outages & Fulfillment Policy

ShipCalm is committed to efficient and reliable order fulfillment. To ensure we meet our service obligations, we follow these policies regarding carrier availability under rate shopped orders :

- **API Availability:** ShipCalm utilizes carrier services only to the extent that their APIs are actively available.
- **Order Continuity:** When a carrier's API goes offline, ShipCalm does not hold orders. Because we cannot predict when a carrier service will be restored, we cannot block fulfillment to wait for specific carrier availability.
- **Next-Best Carrier Logic:** If a specific carrier is unavailable, our system automatically proceeds to the next best carrier option based on standard rate-shopping logic. This ensures your orders continue to be processed and shipped without creating an unmanageable backlog.

 

 

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