Shipping costs are key to e-commerce enterprises’ profitability and long-term viability. You’re wasting money if you’re not sending your products in the most cost-effective and expedient method possible. Flat rate shipping is one approach to cutting delivery costs.
Any shipping solution with a fixed price, such as $10, is known as flat rate shipping. The goal of flat rate shipping is to keep expenses low while your business grows, encourage more consumer purchases, and stay ahead of the competition.
How Does the Flat Rate Box Work?

With a flat-rate box, the weight of a shipment has no bearing on the shipping costs. This will save you money if you transport hefty products. Flat rate delivery, on the other hand, can be costlier if your items are light.
The USPS Priority Flat Charge service provides 1-3 day shipping for one flat rate. Many shippers choose flat rate boxes because it removes the need to weigh the shipments in order to determine shipping charges. If your package weighs less than 70 pounds, it can be shipped via USPS Priority Flat Rate.
These boxes are labeled as USPS flat rate boxes and can be found at various post offices. The boxes themselves are available for free, and you can get as many as you want.
Taking a trip to the postal service and collecting these boxes directly gives you the chance to pick a box that matches the size of your item perfectly. You can speak to the workers at the office about finding the correct size for the items you’re shipping, and they might even point you in the right direction to save money.
You can also have these boxes sent directly to you by the USPS after ordering them online. You, however, need to visit the USPS website and get the flat rate boxes you’ll need for these services (remember, you may order as many as you want at no additional cost). You can contact USPS customer support for assistance in locating the right information, but they aren’t quite as helpful as walking into the post office physically.
With flat-rate delivery, the only thing to keep in mind is that there is a weight limit. The maximum weight was 70 lbs. per flat rate package.
Available Box Sizes and Prices

- Small flat-rate box dimensions are 5 ⅜” x 8 ⅝” x 1 ⅝”. Ships for $7 to $8.
- Medium flat-rate boxes dimensions are 11 ¼” x 8 ¾” x 6″ for top-loading boxes. Ships for $12 to $15.
- Medium flat-rate boxes dimensions are 14″ x 12″ x 3 ½” for side-loading boxes. Ships for $12 to $15.
- Large rate-rate boxes are 12″ x 12″ x 5 ½”. Ships for $17 to $20.
Dual-use priority mail and priority mail express boxes measuring 11 ⅞” x 3 ⅜” x 13 ⅝” are also available.
You may also acquire a four-box variety pack that includes the tiny box, two medium-box variants, and one large box.
USPS Flat Rate envelopes, like boxes, follow the same shipping guidelines. The following sizes are available:
- 10″ x 7″ Gift Card Envelope $6.70 in the mail
- 12 1/2″ x 9 1/2″ flat rate envelope, $6.70 in the mail.
- 15″ x 9 1/2″ Legal Flat Rate Envelope $7.00 in the mail
- 12 1/2″ x 9 1/2″ padded flat rate envelope, $7.25 in the mail
There’s bound to be a box that fits your requirements.
How Can I Benefit from USPS Flat Rate Shipping Services?

The entire procedure for sending flat-rate mail is simple and clear.
Get the Boxes
This will require a trip to the post office or the ordering of boxes from the USPS website. Every local office has boxes of various sizes, as well as envelopes. A straightforward inquiry at the front desk should get you all of the boxes you need right away—and for no cost.
Pack the items
Then you must pack the items you wish to send using the flat rate box. Take into account that you can fill the box up to 70 pounds with anything you choose, including packing materials. If you go above that, you’ll have to pay more.
Even though you’re working with a flat rate box rather than calculated shipping, getting a larger box with extra space is always a smart idea. This lets you store packing materials (like peanuts, foam, etc.) and makes sure that everything stays strong and safe during shipping.
Before sealing the box, check if all the items are well packed. Without charging you extra, the USPS rejects any flat-rate box that cannot close “naturally.” This means that there must be no protrusions or bumps on any flaps. Again, it’s a wise idea to use an oversize box to ensure that even the most unusually shaped objects you wish to ship will fit without issue.
Choose a Method for Sending the Package to Your Courier
The next step is to decide how you want your items sent from your home or courier office.
You can always take the box to the post office yourself, but you may also schedule a home pickup. You can learn how to ship flat rate boxes from home in our article on How to Ship a Package from Home. However, not all post offices provide local pickup services, so make sure to inquire before making your final preparations.
Before you send the package out the door, double-check that the label has been addressed correctly, as specified by the carrier. Preprinted labels can be downloaded from the internet, and there is an online form to have the information entered for you.
A brief trip to the local post office, as always, will ensure that you receive all of the assistance you require from postal officials. They can get all of your shipping information directly from you, enter it correctly, and print and attach the label right away.
Keep in mind that there are other ways you can ship boxes efficiently. You check our guide on How to Boxes for available options.