The official USPS bubble mailer is the Priority Mail Padded Flat Rate Envelope: a free, 12-1/2″ × 9-1/2″ padded envelope that ships at one flat Priority Mail price to any U.S. address, up to 70 lbs. You can also send your own bubble mailer from any store, but USPS then prices it by weight and size, usually as a package through USPS Ground Advantage or Priority Mail.
Which one makes sense depends on how heavy the item is and how fast it needs to arrive. This guide covers the official envelope, the regular bubble mailers you buy yourself, the services that accept each, and how to prepare one so it moves through the mail without trouble.
What Is the USPS Priority Mail Padded Flat Rate Envelope?
It is a Priority Mail envelope lined with bubble-type padding, and it is one of USPS’s free Flat Rate supplies. You pay a single Priority Mail Flat Rate price no matter where it goes in the country or how much it weighs, as long as the item fits with the flap closed normally and the total stays at or under 70 lbs.
Priority Mail includes USPS Tracking and up to $100 of insurance on most shipments, and usps.com lists delivery in 2–3 days. You can order the envelopes free from the USPS Postal Store, and they arrive with your regular mail, usually within 7 to 10 days, or pick them up at many Post Offices.
| Priority Mail Flat Rate envelope | Size | Padded? | Best for |
|---|---|---|---|
| Padded Flat Rate Envelope | 12-1/2″ × 9-1/2″ | Yes | Small fragile or heavy items |
| Flat Rate Envelope | 12-1/2″ × 9-1/2″ | No | Documents and flat goods |
| Legal Flat Rate Envelope | 15″ × 9-1/2″ | No | Legal-size papers |
| Small Flat Rate Envelope | 10″ × 6″ | No | Very small flat items |
USPS’s free Priority Mail packaging may only be used for Priority Mail shipments. If you want to send an item by Ground Advantage, use a bubble mailer you bought yourself. Our page on USPS Flat Rate boxes covers the larger Flat Rate options when an item won’t fit in an envelope.
Can You Ship Your Own Bubble Mailer With USPS?
Yes. Any bubble mailer from an office supply store, the Post Office counter or an online seller can go through USPS, as long as it is sealed and has room for the address, postage and barcode on one flat side.
Most bubble mailers with something inside are priced as packages, not as large envelopes. Under the USPS Domestic Mail Manual, a large envelope (flat) can be no more than 15″ long, 12″ high and 3/4″ thick, and it must be flexible and uniformly thick, with no bumps of more than 1/4 inch. A padded mailer holding a lumpy or rigid item fails those rules. Our guide on whether bubble mailers are considered packages explains the classification in detail.
Which USPS Services Can a Bubble Mailer Use?
A bubble mailer you supply can go by any USPS package service that suits its contents and weight. This table compares the main options.
| Service | Delivery time | Weight limit | Included insurance | Best for |
|---|---|---|---|---|
| USPS Ground Advantage | 2–5 days | 70 lbs | $100 | Light items under a pound |
| Priority Mail (by weight) | 2–3 days | 70 lbs | Up to $100 | Faster delivery |
| Priority Mail Padded Flat Rate | 2–3 days | 70 lbs | Up to $100 | Small, dense items |
| Media Mail | Slower than Ground Advantage | 70 lbs | None | Books, CDs and DVDs only |
USPS Ground Advantage prices packages under 1 lb in weight tiers up to 15.999 oz, which is why it is the usual choice for jewelry, phone accessories and small clothing items in a padded mailer. For heavier but small items, the flat price of the Padded Flat Rate Envelope can be better value. Books and other educational media in a bubble mailer may qualify for USPS Media Mail, which has strict content rules.
For prices by size and weight, see our guide on how much it costs to ship a bubble mailer with USPS, or compare live USPS and UPS prices for your mailer in the ParcelPath rate calculator.
What Bubble Mailer Sizes Work Best for USPS?
Bubble mailers are sold by numbered sizes, which differ slightly between brands. Choose the smallest mailer that closes flat over the item without stretching the seams.
| Common size (inside, approx.) | Good for |
|---|---|
| 4″ × 8″ | Jewelry, USB drives, small parts |
| 6″ × 10″ | Phone cases, cosmetics, cables |
| 8.5″ × 12″ | Paperback books, small electronics |
| 10.5″ × 16″ | Folded clothing, several small items |
| 14.25″ × 20″ | Larger soft goods and bulky items |
Kraft-paper bubble mailers are easy to write on and recycle, while poly bubble mailers resist water better and weigh a little less. Our guide on how much a bubble mailer weighs lists typical empty weights, which count toward the billed weight.
How Do You Prepare a Bubble Mailer for USPS?
A few simple steps keep a padded mailer from jamming in sorting equipment or tearing open in transit.
- Wrap fragile items first. The bubble lining stops scuffs and light knocks, not crushing. Wrap glass or electronics in extra bubble wrap, or use a small box instead.
- Seal the flap completely. Press along the whole adhesive strip, and add packing tape across the flap if the mailer is full.
- Address one flat side. Put the delivery address in the center and the return address in the upper-left corner, with the label lying flat and clear of seams.
- Weigh and measure it. Weigh the sealed mailer on a postal scale and note its thickness, since the weight decides the price tier.
- Buy postage and drop it off. Buy a label online, then drop the mailer at a Post Office, in a collection box if it fits, or hand it to your carrier.
Our USPS packaging guidelines explain what USPS will and won’t accept, and the USPS shipping hub covers every USPS service in one place.
How Can You Pay Less to Ship a USPS Bubble Mailer?
Buying postage online is usually cheaper than paying at the counter. ParcelPath gives up to 89% off USPS retail prices with no subscription, no per-label fee and no minimum volume, and it can schedule free USPS pickups. If you don’t have a printer, use USPS Label Broker: show the code at the Post Office and the clerk prints the label.
Frequently Asked Questions
Does USPS sell bubble mailers?
Yes. USPS gives away the Priority Mail Padded Flat Rate Envelope for free, ordered from the Postal Store or picked up at many Post Offices, but it can only be used for Priority Mail. Many Post Office lobbies also sell regular padded mailers, which you can ship with any service, including USPS Ground Advantage. Office supply stores and online sellers carry them as well.
How big is the USPS Padded Flat Rate Envelope?
The USPS Priority Mail Padded Flat Rate Envelope measures 12-1/2″ × 9-1/2″. It ships at one flat Priority Mail price to any domestic address, as long as the flap closes normally and the total weight is 70 lbs or less. It includes USPS Tracking and up to $100 of insurance on most shipments.
Is a USPS bubble mailer shipped as a package or a large envelope?
Almost always as a package. A large envelope must be no thicker than 3/4 inch, flexible, and uniformly thick, with no bumps over 1/4 inch. Once an item is inside, most bubble mailers fail at least one of those rules, so USPS prices them as packages through services like Ground Advantage or Priority Mail.
Can you put stamps on a USPS bubble mailer?
Yes, you can pay with stamps, but you need the full package price, not the letter price. Weigh the sealed mailer, find the correct USPS Ground Advantage or Priority Mail price, and add enough stamps to cover it. If a stamped mailer weighs more than 10 ounces or is thicker than 1/2 inch, hand it to a Post Office clerk instead of using a collection box.
Sources
- USPS Priority Mail: Flat Rate envelope sizes, insurance and delivery time
- USPS Ground Advantage: delivery time, weight tiers and insurance
- USPS Domestic Mail Manual 101: Physical Standards for letters, flats and parcels
Explore more options in our roundup of the best shipping services and solutions.
Part of our USPS Packaging Guidelines guide. Related: Shipping Resources, USPS Flat Rate Boxes.
