Site Logo (USPS) Carrier Guide with ShipEngine provides access to USPS domestic and international shipping services for packages originating in the United States.

This guide provides developers an overview of shipping services that offers and the service codes that you will use to create these shipments.

Connect Your Account

ShipEngine API allows you to connect your account programmatically without logging in to the ShipEngine API dashboard. This is useful if you have wrapped a custom UI around the ShipEngine API toolset and want to add or disconnect existing carrier accounts without exposing your end users to the API dashboard.

These APIs can be used in parallel with the ShipEngine Partner APIs to programmatically create new ShipEngine users, and then connect existing accounts all via the API without logging into a dashboard. Together these APIs empower you to completely white-label the ShipEngine experience for your end users.

Continue below for instructions on how to programatically connect using the ShipEngine API.

For instructions on connecting a via the ShipEngine dashboard, go to our help article. Account Information Model

usernamestring, required
passwordstring, required

Example POST Call

POST /v1/connections/carriers/stamps_com

POST /v1/connections/carriers/stamps_com HTTP/1.1
Content-Type: application/json
"username": "myusername",
"password": "123456789",

Example Response

"carrier-id": "se-1234567"
} Service Details includes both USPS domestic and international services. Additionally, you can also access GlobalPost international services with a account.

USPS Domestic Services

ServiceTransit TimeMaximum Dimensions (LxWxH)Max WeightService Code
USPS Ground Advantage*2-5 days22" x 18" x 15"70 lbsusps_ground_advantage
USPS Priority Mail1-3 daysvaries by package type70 lbsusps_priority_mail
USPS Priority Mail Express1-2 daysL x 2xW x H cannot exceed 108"70 lbsusps_priority_mail_express
Media Mail2-9 daysL x 2xW x H cannot exceed 108"70 lbsusps_media_mail

*In 2023, USPS Ground Advantage replaced both USPS First Class Package and Parcel Select Ground services.

USPS International Services

ServiceTransit TimeMaximum DimensionsMax WeightService Code
USPS First Class Mail Intl7-21 daysL x 2xW x H cannot exceed 136"64 ozusps_first_class_mail_international
USPS Priority Mail Intl6-10 daysL x 2xW x H cannot exceed 108"70 lbsusps_priority_mail_international
USPS Priority Mail Express Intl3-5 daysL x 2xW x H cannot exceed 108"70 lbsusps_priority_mail_express_international

GlobalPost Services

For all GlobalPost services, transit time will vary depending on the destination country.

ServiceMax WeightService Code
GlobalPost Economy Intl4.4 lbsglobalpost_economy
GlobalPost Standard Intl70 lbsglobalpost_priority
GlobalPost Plus66 lbsgp_plus
GlobalPost SmartSaver Economy Intl4.4 lbsglobalpost_economy_smart_saver
GlobalPost SmartSaver Standard Intl70 lbsglobalpost_priority_smart_saver
GlobalPost Plus SmartSaver66 lbsglobalpost_plus

USPS Package Types

Package NameAPI CodePackage Details
Medium Flat Rate Boxmedium_flat_rate_boxDomestic and international
Flat Rate Envelopeflat_rate_envelopeDomestic and international
Small Flat Rate Boxsmall_flat_rate_boxDomestic and international
Large Flat Rate Boxlarge_flat_rate_boxDomestic and international
Flat Rate Padded Envelopeflat_rate_padded_envelopeDomestic and international
Flat Rate Legal Envelopeflat_rate_legal_envelopeDomestic and international

Example Label

USPS Ground Advantage Example Label

Return Services

Return services are supported for USPS domestic shipments.

Adding Shipment Insurance supports adding insurance to your shipments. Review the Parcel Insurance page for details on adding shipment insurance with ShipEngine.

USPS Advanced Options

Advanced Options are a shipment property used to communicate carrier add-ons used, such as "Saturday Delivery" or "Dangerouse Goods". Carrier Options are available dynamically at the List Carriers endpoint.

OptionNameDefault ValueDescription
Non Machinablenon_machinablefalseIndicates that the package cannot be processed through USPS sorting machines.
Dangerous Goodsdangerous_goodsfalseIndicates this shipment contains dangerous goods

Additional Carrier Details

  • Signature and Adult Signature confirmation types not supported for international shipments.
  • Label messages are supported for domestic shipments only.
  • Voiding labels is supported, but must be done within 28 days of label creation.
  • USPS pickups can only be scheduled for one day in advance. For example, if you schedule a pickup on the 5th for the 7th, the pickup date scheduled by will be the 6th.
  • If you plan to create a USPS SCAN form, you must manifest your day's shipments by 9pm local time.
  • All international shipments using USPS First-Class Mail Int'l, Priority Mail Int'l, or Priority Express Int'l services will use Global Advantage Program labels by default.

Paperless Services

USPS supports paperless labels with their services. This means you can generate a QR code for your customer and they can take that QR code to be scanned at participating USPS locations, who will then print the label for them.

Review our paperless labels page for details on how to generate a QR code instead of a printable label. Currently this supports the qr_code value for the display_scheme property.

Example QR Code


Customer Communications

Using paperless labels might be a new experience for your customers. The USPS suggests sending out an email with the QR code label to help educate your customer on what they need to do to ship their package.

The email containing the QR Code should also include instructions on how to find participating USPS Post Offices by visiting, where the value of the address parameter is customer's ZIP Code (such as 18702 in this example). The USPS Retail Associate at that location's Retail Counter will scan the QR Code and print the shipping label, affix it to the package, and provide a receipt.

If the customer has access to a printer, they may choose instead to print the label directly at, where XYZZYPJK is the Label ID returned by ShipEngine, and 18702 is the ship_from postal_code.

You are now ready to create shipments using via ShipEngine!