The Shipping Secret You Need To Know To Save Money: USPS Flat Rate Envelopes

As a small business running from home, we’re always on the lookout to save money on shipping. One of the best available tools out there that have saved us a ton of money on shipping is USPS Flat Rate Envelopes. We’re not talking about using them just for documents or small, flat items. We use them to ship bulkier items creatively without breaking any of USPS’s guidelines on its usage.

Let us show you how to ship thick items like pants, fabric, and even boxes up to a few inches. We will not be cutting or altering the envelopes in any way. Read on!

USPS Flat Rate Envelope Prices 2021

First of all, let’s look at the three types of USPS Flat Rate Envelopes that we will look at: the Flat Rate Envelope, Legal Flat Rate Envelope, and Padded Flat Rate Envelope. Both the regular Flat Rate and Legal Flat Rate envelopes are made of cardboard. Meanwhile, the Padded Flat Rate Envelope is lined with bubble padding for extra protection.

Flat Rate Envelope Legal Flat Rate Envelope Padded Flat Rate Envelope
Dimensions12 1/2″ x 9 1/2″15″ x 9 1/2″12 1/2″ x 9 1/2″
Weight Limit70 lbs70 lbs70 lbs
Price*Commercial Rate:
USPS Rate:
Commercial Rate:
USPS Rate:
Commercial Rate: $8.00
USPS Rate:

*Price is subject to change as USPS tends to increase the price. This information is updated as of June 2021.

There are also other flat rate envelopes, including:

  • Gift Card Flat Rate envelope
  • Window Flat Rate envelope
  • Small Flat Rate envelope

However, they are all significantly smaller in size but at the same price as the regular Flat Rate Envelope. There is essentially no good reason to pay the same price for a much smaller size packaging. Additionally, you will also see that the Padded Flat Rate envelope is the most expensive.

We do use these for much heavier items like dumbbells that we will go over later. However, we skip them for most other common items to save money and use the regular envelopes instead.

How To Get Commercial Price On USPS Flat Rate Envelopes

Before we get started, you will see that the price of USPS Flat Rate Envelopes is cheaper when you’re able to get commercial pricing instead of buying directly from USPS. So how can you get the commercial rate? By joining a shipping software. It is completely free to join and use in order to get USPS commercial pricing.

The two shipping software that we use is and ship is easier to use if you’re only shipping exclusively with USPS. When you buy your USPS Priority Mail postage from Pirate ship, it comes with $100 of built-in insurance.

Alternatively, if you buy postage from your local USPS store or at, this amount is only up to $50 for Priority Mail. To get up to $100, you will have to use the Priority Mail Express service, which is a lot more expensive. All USPS Flat Rate Envelopes are considered Priority Mail.

If you’re interested in getting shipping discounts with other carriers, such as FedEx, UPS, and DHL Express, Shippo offers all three in addition to the USPS discounts. Shippo also allows you to connect with other regional and international shipping accounts. For a step-by-step of how to use Pirate ship, check here. We also have a comparison of the two here.

Where To Get USPS Flat Rate Envelopes

You can grab USPS Flat Rate Envelopes at your local USPS stores. They are free for you to take home and use. You do not have to pay for them. If your local USPS store does not have the type or size that you’re looking for, you can order them directly from

They will ship it to you for absolutely free to your home. If you need help navigating USPS’s website to order your USPS supplies, check this post here.

How NOT To Use USPS Flat Rate Envelopes

You cannot alter USPS Flat Rate Envelopes in any way. Altering in this context means you cannot cut around them and add any amount of dimensions and then retaping them. The flat rate envelopes must be able to close without the contents bulging out. You must be able to close the flaps the way USPS designed them.

If you are using these flat rate envelopes, you must ship them at the flat rate envelope price. For example, you cannot use these flat rate envelopes to ship First Class. You also cannot use these flat rate envelopes to ship regular Priority Mail. Additionally, you cannot use your own envelopes or boxes to ship at the flat rate price. We will still follow these guidelines when we ship our items.

Why Use USPS Flat Rate Envelopes

The biggest reason for using USPS Flat Rate Envelopes is to save money on shipping. Normally, the shipping cost will be dependent on the package’s weight, dimensions, and distance. Usually, the higher the number is on any of the three mentioned, the higher the shipping price.

Shipping with a Flat Rate envelope will save you money when your package has to travel long distances while weighing more than 1 pound.

If your package is below 1 pound, you will want to ship First Class, no matter the distance. That is why it is very important to know your package’s weight and dimensions. Make sure you have a shipping scale and measuring tape. They will save you money over the long run.

How To Ship Bulky Items With USPS Flat Rate Envelope

Finally, here is the USPS shipping secret that will save you a ton of money.

Keep in mind the flat rate envelope refers to the rate, not the shape.

While you cannot alter the envelope, there is nothing against reshaping the envelope in a way that makes packaging easier. In our example here, we will be shipping a pair of men’s jeans.

You can certainly use the Padded Flat Rate Envelope to ship this without any challenge. However, we will use the regular Flat Rate Envelope to save $0.60. This amount may not be much for an individual package but when you’re shipping tens of packages per day, hundreds of packages per month, this cost adds up! Without this trick, it is a lot harder, if not impossible to get this pair of jeans inside and closed. So here’s what you need to do.

1. Fold the bottom

You want to fold enough to be the thickness of the item that you’re trying to ship. With a pair of jeans, it is about an inch.

2. Fold both sides

Repeat your folds on both sides of the envelope. This is again about an inch on both sides.

3. Reshape the envelope to a box by pressing on the folds

This is the most important step here. Time for a little origami! First, open the envelope. Then, carefully press out the box by where you have made the folds. You will see that it will start being shaped like a box with a base and two folds on the side. You will now have enough room for the pants!

4. Insert the item

We can now easily fit the pants inside. So slide the pants in the newly formed “box”.

5. Peel off the adhesive and close

Next, fold the flap over, peel the adhesive strip, and close the envelope. Make sure you press the flap to be as flat as possible.

6. Press the folds back down

The next step is to flatten your entire envelope, including the lines where you have folded them. Your package should now look like a regular envelope, just a little thicker. Remember, the Flat Rate refers to the rate, not the shape of the item. We did not alter the envelope in any way that it was not meant for.

7. Reinforce with tape

There is nothing wrong with reinforcing the closure with tape. Carriers are often known to be rough with packages during transit. These packages are often tossed. We always reinforce the closure, especially during the heat of summertime, which could melt the adhesive between the cardboards. Otherwise, you’re done!

What About USPS Legal Flat Rate Envelope And Padded Flat Rate Envelope?

The cheapest shipping rate among the flat rate envelopes is the regular Flat Rate Envelope that we used in our example. So when would you use the Legal Flat Rate Envelope? If we have clothing or other items that are a little too long for the regular envelope, we will use the Legal Flat Rate Envelope.

When it comes to the Padded Flat Rate Envelopes, we use them to ship much heavier items. That is because they tend to be more secure than cardboard envelopes. For example, we would ship a pair of dumbbells without worrying about the padded envelope being torn.

As with other cardboard envelopes, we would still reinforce the seams with tape. Again, we’re not altering the envelope in any way that is not allowed.

Other Shipping Tips To Know

As with all our shipping tips, we want to remind you that you are eligible for shipping insurance if USPS loses or damages your mail while in transit. Remember that when you ship with USPS Flat Rate Envelopes, they come with built-in insurance because they are a Priority Mail service. We show you how to file your USPS insurance claim here.

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