USPS Flat Rate Box Sizes, Prices, and How it Works (2024)

Editors note: This blog was last updated February, 2024.

USPS Priority Mail Flat Rate boxes are an easy-to-use,cost-effective shipping option. You can easily ship like the experts; just know the USPS Flat Rate box sizes, prices, and how it works before you buy.

How Does USPS Flat Rate Shipping Work?

The USPS Priority Mail Flat Rate service will ship your package anywhere in the U.S. in 1-3 business days for a flat fee. To ship with this service, follow these easy steps:

What are the 2024 USPS Flat Rate Box Sizes and Prices?

As you’ll see below, Shippo offers discounted shipping rates when compared to what you’d find at your local Post Office. No volume or coding requirements. On top of this, Shippo merchants get access to special pricing on Priority Mail Flat Rate services during peak season. Sign up for a free Shippo account, to see live discounted rates and print USPS labels for Flat Rate Boxes.

2024 USPS Priority Mail Flat Rate
Shippo vs. Retail Rates
ProductsDimensionsShippo RateRetail RateSavings Using Shippo vs. Retail

% Savings with Shippo

Flat Rate Envelope12 ½” x 9 ½”$7.99$9.85$1.8620.85%
Legal Flat Rate Envelope15” x 9 ½”$8.27$10.15$1.8820.41%
Padded Flat Rate Envelope12 ½” x 9 ½”$8.74$10.60$1.8619.23%
Small Flat Rate Box

8 11/16” x 5 7/16” x 1 ¾”

$8.51$10.40$1.8919.99%
Medium Flat Rate Box

11 ¼” x 8 ¾” x 6”

$14.38$18.40$4.0224.53%
Large Flat Rate Box

12 ¼” x 12 ¼” x 6”

$19.51$24.75$5.2423.68%
APO/FPO/DPO Lg. Box

12 ¼” x 12 ¼” x 6”

$18.35$20.15$1.809.35%

Some notes to take into account when choosing which Flat Rate options to choose:

  • Flat Rate Envelope: Best for 1-70 lbs
  • Legal Flat Rate Envelope: Best for 2-70 lbs
  • Padded Flat Rate Envelope: Best for 2-70 lbs
  • Small Flate Rate Box:Best for 1-20 lbs AND zones 5-9 as well as 21-70 lbs (all distances)
  • Medium Flat Rate Box: Best for 3-20 lbs AND zones 7-9 as well as 21-70 lbs (all distances)
  • Large Flat Rate Box: Best for 5-20 lbs AND zones 8-9 as well as 21-70 lbs (all distances)
  • APO/FPO/DPO Large Box: Best for 1-70 lbs

We'll walk through these examples a little further below.

Is Priority Mail the Same as Flat Rate?

USPS Priority Mail is one of the most popular service levels the Postal Service offers, and for good reason. It’s cost-effective and encompasses three widely-used shipping options: Priority Mail Flat Rate (which we discussed above), Priority Mail weight-based, and Priority Mail Cubic.

To ship via Flat Rate, you need to use the Flat Rate branded boxes. To use Cubic and weight-based options, you must use your own packaging or USPS Priority Mail boxes.

Which is Cheaper: Flat Rate or Priority Mail?

Generally speaking, the USPS Flat Rate boxes are a great option for heavy items that are traveling long distances.We ran the numbers to find out exactly when you should use a Flat Rate box and when you should use your own packaging and ship via USPS Priority Mail weight-based or Cubic instead.

When to Use USPS Flat Rate Envelopes

  • USPS Flat Rate Envelopes are almost ALWAYS the cheapest option.
  • However, use your own envelope for packages weighing exactly 1 lb. and traveling locally.
  • And if your package weighs less than 1 lb., use your own envelope and ship via USPS First-Class Package Service.

Use your own envelope (NOT a Flat Rate envelope) for the following scenarios:

Flat Rate Envelope (12 1/2″ x 9 1/2″) – $7.99
Qualifications for Using Own PackagingCost to ShipSavings
Weighs 0.5-1 lb. and traveling less than 50 miles (Zone 1)$6.64$1.35
Legal Flat Rate Envelope (15″ x 9 1/2″) – $8.27
Qualifications for Using Own PackagingCost to ShipSavings
Weighs 0.5-1 lb. and traveling 500 miles (Zone 4)$6.88$1.39
Padded Flat Rate Envelope (12 1/2″ x 9 1/2″) – $8.74
Qualifications for Using Own PackagingCost to ShipSavings
Weighs 0.5-1 lb. and traveling 500 miles (Zone 4)6.88$1.86
Weighs 2 lbs. and traveling less than 50 miles (Zone 1)$6.65$2.09

When to Use USPS Flat Rate Boxes

  • For 1 – 20 lb. packages, choose Flat Rate for long distances and your own box for short distances.
  • For <1 lb. packages, use your own box and ship via USPS First-Class Package Service.
  • For >20 lb. packages, use a Flat Rate box.

Use your own box (NOT a Flat Rate box) for the following scenarios:

Sm. Flat Rate Box (8 11/16″ x 5 7/16″ x 1 3/4″) – $8.51
Qualifications for Using Own PackagingCost to ShipSavings
Weighs 2 lbs. and traveling 500 miles (Zone 4)$6.89$1.62
Med. Flat Rate Box (11 1/4″ x 8 3/4″ x 6″) – $14.38
Qualifications for Using Own PackagingCost to ShipSavings
Weighs 1 lbs. and traveling 2,000 miles (Zone 8)$9.43$4.95
Weighs 10 lbs. and traveling 1030 miles (Zone 6)$8.18$6.20
Lg. Flat Rate Box (12 1/4″ x 12 1/4″ x 6″) – $19.51
Qualifications for Using Own PackagingCost to ShipSavings
Weighs 0.5-1 lb. and traveling to (Zone 8)$10.07$9.44
Weighs 3 lbs. and traveling to (Zone 8)$17.26$2.25
Weighs 4 lbs. and traveling to (Zone 7)$17.45$2.06

Keep in mind that the maximum weight is 70 pounds. And, when sealing a Flat Rate envelope or box, the container flaps must be able to close within the normal folds.

Is Priority Mail (Weight-based) or Flat Rate Faster?

Technically speaking, they are all part of the Priority Mail mail stream, so they all ship within 1-3 business days.

Are There Any Other Restrictions?

There are specific regulations and standards for mailing restricted, prohibited, and hazardous materials, including cigarettes and smokeless tobacco. You also can’t ship airbags, ammunition, explosives, or gasoline. For more details, visit the USPS Shipping Restrictions page.

How Do I Get a USPS Priority Mail Flat Rate Label?

Setting up a free Shippo account takes just a few minutes, and then you can print the label from your office or warehouse. (Feel free to check out our USPS shipping calculator to get a clearer picture of how you can save on USPS shipping rates by using Shippo.) Affix the label to the USPS Priority Mail Flat Rate box. Then, put it in your mailbox or schedule a pick-up with your local mail carrier in the Shippo dashboard.

Make sure the label you’re using matches the packaging. For example, if you use a Priority Mail Express Flat Rate box, you need to use a Priority Mail Express Flat Rate label.

If you liked this post, you may also be interested in a video that our co-founder Laura Behrens Wu did with the co-founder of packaging solution company Lumi on shipping with the USPS.

Shippo is a multi-carrier API and web app that helps retailers, marketplaces, and platforms connect to a global network of carriers. Businesses use Shippo to get real-time rates, print labels, automate international paperwork, track packages and facilitate returns. Shippo provides the tools to help businesses succeed through e-commerce shipping.

Michelle McNamara

is a Senior Marketing Manager at Shippo

Sign up for the Shippo newsletter

Loading...

Thanks for your submission!

USPS Flat Rate Box Sizes, Prices, and How it Works (2024)

FAQs

USPS Flat Rate Box Sizes, Prices, and How it Works? ›

For shipments traveling shorter distances, Zones 1-4, and weighing less than 20 lbs, using your own packaging for weight-based rates may be a better value. Across all zones, though, shipments weighing over 16 lbs will ship for less in a Flat Rate Medium Box.

Is it cheaper to use a flat rate box or your own box USPS? ›

For shipments traveling shorter distances, Zones 1-4, and weighing less than 20 lbs, using your own packaging for weight-based rates may be a better value. Across all zones, though, shipments weighing over 16 lbs will ship for less in a Flat Rate Medium Box.

What are the sizes and prices of USPS flat rate boxes? ›

Priority Mail Flat Rate Products
Free Supplies8Shipping Price
Legal Flat Rate Envelope$8.80 Commercial Pricing $10.15 at Post Office
Small Flat Rate Box$9.05 Commercial Pricing $10.40 at Post Office
Medium Flat Rate Box — 1 (top-loading)$16.00 Commercial Pricing $18.40 at Post Office
9 more rows

How do USPS flat rate boxes work? ›

How does flat rate shipping work? To use USPS flat rate shipping, you need to get a USPS flat rate box from your local USPS office (small, medium, or large size), add no more than 70 pounds of contents that fit inside the box, label an address, and ship the box at a USPS office using Priority Mail.

Which is cheaper, priority mail or flat rate? ›

If you are primarily shipping products locally across short distances, opting for Priority Mail services rather than Fixed Rate might make sense. If your shipments generally cover a long distance or you are shipping all across the US, Flat Rate envelopes and boxes will often work out to be cheaper.

Is USPS getting rid of flat rate boxes? ›

Effective January 22, 2023, Regional Rate Box pricing has been discontinued. Remaining Regional Rate Boxes can still be used for shipping, but they will be treated as weight and rate packages.

Can I use a USPS flat rate box but use my own shipping? ›

Can customers use the flat-rate box for other mailing services? No. The flat-rate box is clearly marked and can be used only for Priority Mail items at the $7.70 Priority Mail flat- rate box rate.

Can I pick up flat rate boxes at the post office? ›

USPS offers their priority mail boxes and envelopes for free. There is no cost for picking up these priority boxes, but you must use them for the proper form of priority mail shipping. You can pick up flat rate boxes in-person from any post office. Authorized USPS shippers may also have the boxes available.

What is the cheapest way to ship a package? ›

The cheapest way to ship a package will depend on factors such as package size and weight, as well as distance and delivery speed. Generally, USPS Ground and Priority Mail are the most affordable shipping options.

Can I use a flat rate box but pay by weight? ›

USPS Flat Rate is a class of packaging that provides specific-sized boxes and envelopes for use with USPS Priority Mail services. They can be shipped anywhere in the US for one flat fee regardless of weight, so long as the parcel weighs fewer than 70 lbs.

Do I need to print a label for a flat rate box? ›

Once your label is generated, you need to print it out (no special printer or paper usually required), attach it to the package and drop it off at a post office or schedule a pickup. It is important that your shipping label matches the flat rate box you've chosen.

Can I prepay a USPS flat rate box? ›

Free packaging: You can get flat rate packaging free of charge at your local post office or order online from the Postal Store. USPS flat rate envelopes are offered in packs of 10 and boxes are available in packs or 10 or 25. Forever prepaid boxes and envelopes are also available.

What fits in a medium flat rate box? ›

Priority Mail® Medium Flat Rate Box

Available in two sizes: 11 inches x 8½ inches x 5½ inches (top-loading) - Perfect for model cars, shoes, and taller items. 13⅝ inches x 11⅞ inches x 3⅜ inches (side-loading) - Ideal for garments, board games, books, and other relatively thin items.

Does weight matter with flat rate boxes? ›

Weight restrictions for domestic Priority Mail Express Flat Rate Envelopes, and Priority Mail Flat Rate Envelopes and Boxes are 70 pounds. Weight restrictions for Priority Mail Express International Flat Rate Envelopes are 4 pounds.

What are the current USPS flat rate prices? ›

Competitive:
  • Product. Current. Jan. 22nd 2023.
  • Small flat-rate box. $10.40. $10.20.
  • Medium flat-rate box. $17.05. $17.10.
  • Large flat-rate box. $22.45. $22.80.
  • APO/FPO large flat-rate box. $20.95. $21.20.
  • Regular flat-rate envelope. $9.90. $9.65.
  • Legal flat-rate envelope. $10.20. $9.95.
  • Padded flat-rate envelope. $10.60. $10.40.

Can I bring my own box to the USPS? ›

If you use your own envelope or box for Priority Mail, identify it with the marking, "Priority Mail." Priority Mail packaging provided by the USPS must be used only for Priority Mail.

What is the cheapest way to ship USPS? ›

First-Class Mail® is an affordable mail service for standard-sized, single-piece envelopes weighing up to 3.5 oz and large envelopes weighing up to 13 oz. Prices start at $0.68 at a Post Office.

Is it cheaper to use your own box for UPS? ›

However, using a UPS box can often result in lower shipping rates compared to using your own box, as UPS offers discounts on shipping when you use their boxes. Another benefit of using UPS boxes is that they come in a variety of sizes and shapes, making it easier to find the perfect fit for your shipment.

Is it cheaper to ship by weight or box size? ›

You'll pay for USPS shipping (or shipping with other carriers) based solely on the actual package weight. However, if you ship something relatively light in a large box, you may pay more than you expected. Read on for examples of how DIM weight pricing can affect your USPS shipping costs.

Is it cheaper to mail two smaller boxes or one large box? ›

If possible, it's often better to ship two smaller boxes rather than one large, heavy box. This will spread the weight of your cargo over two smaller parcels, which can significantly reduce your shipping costs especially if the large box would qualify for large or oversized pricing.

References

Top Articles
Latest Posts
Recommended Articles
Article information

Author: Horacio Brakus JD

Last Updated:

Views: 5327

Rating: 4 / 5 (51 voted)

Reviews: 82% of readers found this page helpful

Author information

Name: Horacio Brakus JD

Birthday: 1999-08-21

Address: Apt. 524 43384 Minnie Prairie, South Edda, MA 62804

Phone: +5931039998219

Job: Sales Strategist

Hobby: Sculling, Kitesurfing, Orienteering, Painting, Computer programming, Creative writing, Scuba diving

Introduction: My name is Horacio Brakus JD, I am a lively, splendid, jolly, vivacious, vast, cheerful, agreeable person who loves writing and wants to share my knowledge and understanding with you.