USPS First Class Box Sizes & Prices

USPS First Class allows merchants to ship items for a fixed price, irregardless of weight when using specific packaging.

Ensure the right rate is selected when you sign up for an Easyship account.

USPS Priority Mail Domestic Flat Rate

Package Type
Flat Rate Envelope
12 1/2" x 9 1/2"
Gift Card Flat Rate Envelope
10" x 7"
Window Flat Rate Envelope
10" x 6"  or  12 1/2" x 9 1/2"
Small Flat Rate Envelope
10" x 6"
Padded Flat Rate Envelope
12 1/2" x 9 1/2"
Legal Flat Rate Envelope
15" x 9 1/2"
Small Flat Rate Box
8 11/16" x 5 7/16" x 1 3/4"
Medium Flat Rate Box – 1 (top-loading)
11 1/4" x 8 3/4" x 6"
Medium Flat Rate Box – 2 (side-loading)
14" x 12" x 3 1/2"
Large Flat Rate Box
12 1/4" x 12 1/4" x 6"
APO/FPO/DPO Flat Rate Box
12 1/4" x 12 1/4" x 6"
Large Flat Rate Board Game Box
24 1/16" x 11 7/8" x 3 1/8"
Flat Rate Envelope (Express)
12 1/2" x 9 1/2"
Legal Flat Rate Envelope (Express)
15" x 9 1/2"
Padded Flat Rate Envelope (Express)
12 1/2" x 9 1/2"

Shipping with USPS First Class


Based on key criteria from users and recipients, USPS First Class has the following ratings

  • Support:
  • Tracking:
  • Speed:
  • Overall:
Market Served: Domestic

Common questions about USPS First Class

How does USPS First Class work?

To create a shipment with USPS First Class, you must enter your shipment details (such as address and item details) and purchase a shipping label. Print out your shipping labels and attach to your package and then dropoff your package at a designated dropoff location. Dropoff locations can be found here. From there, USPS will arrange shipment to your final destination.

This whole process can be managed on the Easyship platform.

How do I track a USPS First Class shipment?

You can track USPS First Class shipments using the tracking number for the shipment provided and visiting the USPS website.

How do I contact USPS for a shipment?

When shipping with Easyship you do not need to contact USPS. All the information you need about your shipments is available to you through the Easyship platform. If you want to learn more about USPS you can learn more at their website or calling 1-800-275-8777.

What are the shipping rates for USPS First Class?

Pricing varies based on shipment details and destination.

Signup today for a free Easyship account to see the most accurate rates for USPS First Class and other services we offer.

How long will delivery take for a USPS First Class shipment to United States?

Delivery time varies on origin and destination.

Signup for an Easyship account to see delivery time for all available couriers in your location.

Is there a USPS location near me?

You can find the full list of USPS locations in United States here.

What can I ship with USPS First Class?

USPS First Class do not have many restrictions on what you can ship, however you should be mindful that things such as alcohol, food & other items are generally restricted to most locations. With USPS First Class, stand-Alone Batteries are not allowed

Does USPS First Class require a signature on delivery?

USPS First Class shipments do require a signature on delivery. For a delivery to be completed, somebody will need to be at the destination address to receive the shipment.

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