Parcel Size FAQs

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See also:

Are dimensions required on all parcel types?

Dimensions are required for the following:

  • PB Expedited (USPS®): USPS encourages shippers to provide dimensions for all packages. Dimensions are required for shipments that use the SOFTPACK parcel type or use the Parcel Select—Ground service.

  • PB Deivery

  • PB Presort

  • PMOD

When creating a shipment, assign dimensions in the dimension object.

Important: Entering incorrect dimensions might result in an undeliverable package or an additional postage fee.

How are dimensions ordered?

The dimension object orders dimensions as follows, from longest to shortest.

  1. Length is the longest dimension.

  2. Height is the next longest.

  3. Width is the shortest.

If you assign values differently when creating a shipment, the APIs will reassign them in the order above.

For example, if you have a parcel that measures 6 x 4 x 1 inches, and if you assign 1 inch to the height:

"length": "6.0", "width": "4.0", "height": "1.0"

The API will reassign the values to assign 1 inch to the width:

"length": "6.0", "width": "1.0", "height": "4.0"

How is girth calculated?

Girth is twice the sum of the height and width:

girth = 2 * (height+width)

Note: The APIs configure length as the longest dimension, followed by height, followed by width.

What are the allowed dimensions for USPS parcel types?

To retrieve the dimensions for the parcel types for each USPS Service, use the Carrier Rules API.

See also the following USPS pages:

Important: For the PKG parcel type, the dimensions of the parcel may affect its cost. Measure the length, height, and width accurately to avoid receiving an adjustment for underpayment based on USPS Automated Package Verification.

Can I ship irregular parcels and non-machinable letters through USPS?

To ship irregular parcels and nonmachinable letters through PB Expedited, do the following:

  1. Contact the Client Support team and request to be enabled to ship irregular parcels and non-machinable letters through USPS. Contact Client Support at or +1 844 470-6626.

  2. Once you have been enabled, do the following to ship irregular parcels and non-machinable letters:

    • For Irregular Parcels: Set the following fields to the following values:


      Set this to UGA


      Set this to IRRPKG


      Set this to the correct dimensions. Dimensions are required for irregular parcels.

      In the API response, the fee appears as an irregular surcharge in the rates.surcharges array. The fee is included in the amount listed in the rates.totalCarrierCharge field.

      The word “SURCHARGE” appears in the indicia section of the shipping label.

    • For Nonmachinable Letters: Set the following fields to the following values:


      Domestic shipments: set to FCM
      International shipments: set to FCMI


      Domestic shipments: set to NMLETTER
      International shipments: set to NMLTR

      The surcharge is included in the rates.totalCarrierCharge amount in the response.