Launch Announcement: Dimension Normalization for Shipment Requests WW

Amazon Shipping will automatically normalize package dimensions submitted via the Shipping API V2 for WW including US, UK, France, Italy, Spain (FRITES) and India marketplaces for services of Amazon shipping as carrier for both On-Amazon and Off-Amazon type shipments.

What is changing?

Amazon Shipping now normalizes package dimensions submitted in the getRates and oneClickShipment APIs. Dimensions are automatically sorted in descending order so that length ≥ width ≥ height, consistent with the Amazon Shipping Service Guide definition:

Note: "Length is defined as the longest side of the parcel."

If you submit width: 40, length: 20, height: 30, the API will normalize this to length: 40, width: 30, height: 20.

Which marketplaces are affected?

This feature is available WW for US, UK, France, Italy, Spain (FRITES), and IN marketplaces.

Region	Availability
IT, ES, FR	Live
US	Live
UK	Live
IN	April 2026

Who is affected?

All shippers using the getRates or oneClickShipment endpoints who submit package dimensions. This applies to any integration that passes length, width, and height in the Dimensions object.

What action is required?

No action is required. This change enforces existing policy — dimensions have always been defined as length ≥ width ≥ height per the Service Guide. Packages already submitted in the correct order are unaffected.

This change does not affect:

Pricing or rate calculations
Billable weight
Volume calculations

Technical Details

The Dimensions schema in the Shipping API V2 now applies server-side normalization:

Before normalization:

{
  "dimensions": {
    "length": 10,
    "width": 25,
    "height": 15,
    "unit": "CM"
  }
}

After normalization (as processed by the API):

{
  "dimensions": {
    "length": 25,
    "width": 15,
    "height": 10,
    "unit": "CM"
  }
}

Note: Package dimensions are normalized upon submission across all marketplaces:

1- The largest value is assigned to length, the middle to width, and the smallest to height (descending order: length ≥ width ≥ height).

2- Length is defined as the longest side of the package.

3- Units are preserved. Submitted dimension field assignments may be reordered accordingly.

Updated Dimensions Schema:

Field	Type	Description
`length`	`number`	Longest side of the package. Normalized to be ≥ width and height.
`width`	`number`	Second-longest side. Normalized to be ≥ height.
`height`	`number`	Shortest side of the package.
`unit`	`string`	Unit of measurement (`CM` or `IN`).

FAQs

Will this change my shipping rates?
No. Rates are calculated based on the same dimensions — normalization only reorders the field assignment, not the values themselves.
Does it apply to other carrier services as well?
No, this change is applicable to Amazon Shipping Carrier services only.
Do I need to update my integration?
No. This is a server-side change. Your existing API requests will continue to work without modification.
What if I already submit dimensions in the correct order?
Nothing changes for you. Normalization is a no-op when dimensions are already sorted descending.
Does this affect label generation or tracking?
No. Normalization applies only to how dimensions are interpreted for routing and conveyance. Labels, tracking, and delivery are unaffected.

Additional Resources

Shipping API V2 Reference — Dimensions