Shipping & Rates FAQ

How long do I have to ship a package after creating the label?

Ideally, you will ship the package on the same day that you create the label. If the date on the label has passed and the package has not shipped, this delay can interfere with the timeframe required to deliver a shipment. Carriers may accept packages within a couple of days past the ship date on the label, but we cannot guarantee that all locations and carriers will allow this.

We recommend setting the Ship Date to the date that you actually plan to ship the package.

When you create a label, the Ship Date automatically populates with the current date or the next shipping date, depending on the carrier's cut-off time. Manually overwrite this date with one of your choosing by including a ship_date parameter in your request.


When the USPS is closed for holidays and events, ShipEngine may automatically set the date forward to the next USPS business day.

What are USPS Postal Zones?

USPS uses Postal Zones, numbered from 1-9, to estimate the distance between an origin and destination address. Zone 1 is a local shipment, and Zone 9 is the furthest possible distance between locations for a domestic shipment.

When you request a rate in the ShipEngine API with USPS services, you might get a value back for the zone in the response. For example:

    "zone": 5,   
    "package_type": null,   
    "delivery_days": 3,   
    "guaranteed_service": false,   
    "estimated_delivery_date": "2020-04-11T00:00:00Z",   
    "carrier_delivery_days": "3",   
    "ship_date": "2020-04-08T00:00:00Z",   
    "negotiated_rate": false,   
    "service_type": "USPS First Class Mail",   
    "service_code": "usps_first_class_mail",   
    "trackable": true,   
    "carrier_code": "endicia",   
    "carrier_nickname": null,   
    "carrier_friendly_name": "Endicia",   
    "validation_status": "valid",   
    "warning_messages": [],   
    "error_messages": []

What is Dimensional Weight Pricing?

Dimensional Weight, also called DIM weight or volumetric weight, is a pricing method that uses an estimated weight calculated from the length, width, and height of a package divided by a specific divisor determined by the carrier.

For certain carriers, like UPS and FedEx, a shipment's billable shipping cost is calculated based on dimensional weight, if that value is higher than the actual weight.

To ensure you are receiving accurate shipping quotes on these services from FedEx and UPS, we recommend that you enter a package's total weight and package dimensions. This way, ShipEngine quotes should reflect those that UPS and FedEx provide on their websites to logged-in users.

Can I add insurance to my shipments?

Yes! ShipEngine offers the following insurance options when configuring shipments:

  • Carrier insurance: Use this option to add the carrier's insurance to your package. This is not necessary if you want only the service's default insurance.

  • Shipsurance: Use this option to add Shipsurance insurance to your package. Shipsurance is a ShipEngine partner and is pre-loaded into your ShipEngine account. Funds are purchased with the credit card on file for your ShipEngine account. Learn more about Shipsurance.

  • Other: Use this option to indicate on your shipment record that you have purchased insurance for this package from a third-party insurance provider.

Learn more about using insurance with ShipEngine.

How do rates work in ShipEngine?

ShipEngine offers two distinct endpoints for rate quotes: the Rates endpoint and the Estimate a Rate endpoint. When using either endpoint, shipment information is provided in the request and a rate will be returned. Rates are determined by your connected carrier accounts.

If the shipment details are not accurate or complete, the carrier reserves the right to adjust the rate charged to your monthly invoice, or to charge an adjustment fee for pay-on-create labels.

The following factors can change a shipment’s rate from what ShipEngine displayed at the time of label purchase:

  • Residential vs. commercial address determination

  • Inaccurate weight entered into ShipEngine

  • Drop-off type incorrect

  • Incomplete information for the origin address

  • Dimensional weight applies but no dimensions added in ShipEngine

Rates vs. Rate Estimates

The  Estimate a Rate endpoint will provide an estimated rate from the carrier. Estimates do not include additional charges from the carrier (such as fuel surcharges, customs charges, or other carrier-imposed fees).

The Rates endpoint provides a more accurate rate quote from the carrier, which is why more information is required in the request.

Does ShipEngine offer any discounted rates?

ShipEngine offers discounted rates for both USPS and UPS services. These services are included in a bundled account called ShipEngine Carriers.

You can also connect your own carrier accounts and use any negotiated rates you may have with those accounts.

Why are the rates in ShipEngine different from the rates in my carrier account?

Below are the most common reasons you would see different rates in ShipEngine:

  • There is a mismatch between shipment details in the ShipEngine rate request and your carrier's web portal.

  • You have not enabled negotiated rates in ShipEngine for UPS.

  • You have a different pickup type set up in ShipEngine than your UPS account.

If you are still seeing any rate discrepancies after reviewing these common causes, please contact ShipEngine support.