Carrier Packaging



Package Basics

When you use a carrier package, this can affect things like your rate (e.g. USPS Flat Rat Boxes). Additionally, you cannot provide any dimensions for the package in the shipment. For this example, we're going to use USPS and send a medium_flat_rate_box.

Simply add the objects directly into the shipment object. This is the same format to use when getting shipping rates as well.


POST /v1/labels/

Instead of using custom packaging, we'll send this shipment using a USPS Medium Flat Rate Box, all we need to know to send that box is the weight, which is still 9.6 ounces.

POST /v1/labels HTTP/1.1
Content-Type: application/json

  "shipment": {
    "service_code": "usps_priority_mail",
    "ship_to": {
      "name": "Amanda Miller",
      "phone": "555-555-5555",
      "address_line1": "525 S Winchester Blvd",
      "city_locality": "San Jose",
      "state_province": "CA",
      "postal_code": "95128",
      "country_code": "US",
      "address_residential_indicator": "yes"
    "ship_from": {
      "company_name": "Example Corp.",
      "name": "John Doe",
      "phone": "111-111-1111",
      "address_line1": "4009 Marathon Blvd",
      "address_line2": "Suite 300",
      "city_locality": "Austin",
      "state_province": "TX",
      "postal_code": "78756",
      "country_code": "US",
      "address_residential_indicator": "no"
    "confirmation": "none",
    "insurance_provider": "none",
    "packages": [
        "package_code": "medium_flat_rate_box",
        "weight": {
          "value": 9.6,
          "unit": "ounce"

We added the shipment_package[0].package_code and removed shipment_package[0].dimensions:

  "package_code": "medium_flat_rate_box"
  "label_id": "se-test-41844486",
  "status": "processing",
  "shipment_id": "se-41844486",
  "ship_date": "2019-07-25T05:00:00.000Z",
  "created_at": "2019-07-25T15:24:46.657Z",
  "shipment_cost": {
    "currency": "usd",
    "amount": 0.0
  "insurance_cost": {
    "currency": "usd",
    "amount": 0.0
  "tracking_number": "9999999999999",
  "is_return_label": false,
  "is_international": false,
  "batch_id": "",
  "carrier_id": "se-0",
  "service_code": "usps_priority_mail",
  "package_code": "medium_flat_rate_box",
  "voided": false,
  "voided_at": null,
  "label_format": "pdf",
  "label_layout": "4x6",
  "trackable": true,
  "carrier_code": "stamps_com",
  "tracking_status": "unknown",
  "label_download": {
    "pdf": "",
    "png": "",
    "zpl": "",
    "href": ""
  "form_download": null,
  "insurance_claim": null

You can now print your label and ship it! Your label can be found by navigating to label_download.href.