USPS Flat Rate Boxes, Envelopes, & Pricing

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What are USPS Flat Rate Boxes & Envelopes?

USPS Flat Rate Boxes & Envelopes are just that - boxes and envelopes with flat postage rates, no matter how heavy the package is. If you're shipping heavy, small items, Flat Rate Boxes & Envelopes are the best bang-for-your-buck option. Take advantage of USPS flat rates by keeping a supply of these around your fulfillment operations. USPS provides these flat rate boxes and envelopes for free at most Post Offices or will ship them to you at the USPS Store. Using a USPS Flat Rate Box or Envelope can cut your shipping costs by 50%. This is a great way to prepare for peak shipping.

In addition to large Flat Rate Boxes, small Flat Rate Boxes and medium Flat Rate Boxes, prices are supported through the EasyPost API by using our predefined packages. So it's easy to set up internally and start collecting savings from your Flat Rate Boxes & Envelopes as soon as you integrate with EasyPost.

What is the Postage Cost For USPS Flat Rate Boxes & Envelopes?

We've broken the pricing into the table below. Note: The rates below reflect USPS Commercial Plus Pricing, which is available when shipping via EasyPost. If you're interested in signing up for USPS Commercial Plus Pricing, contact us and we can set you up.

USPS Priority Mail Flat Rate Options

Last Updated: July 10, 2022.

TypeSize*EasyPost Predefined PackagePrice
Envelope12 ½" x 9 ½"FlatRateEnvelope$7.75
Window Envelope10" x 5" or 12 ½" x 9 ½"FlatRateWindowEnvelope$7.75
Small Envelope10" x 6"SmallFlatRateEnvelope$7.75
Padded Envelope12 ½" x 9 ½"FlatRatePaddedEnvelope$8.45
Legal Envelope15" x 9 ½"FlatRateLegalEnvelope$8.05
Small Box8 1116" x 5 716" x 1 ¾"SmallFlatRateBox$8.25
Medium Box11 ¼" x 8 ¾" x 6" or 14" x 12" x 3 ½"MediumFlatRateBox$14.25
Large Box12" x 12 ¼" x 6"LargeFlatRateBox$19.20
APO/FPO Box12" x 12 ¼" x 6"LargeFlatRateBoxAPOFPO$17.70

* Outside dimensions

If you have any questions about our Commercial Plus Pricing use the button below to contact us.

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