How Many Stamps for a Bubble Mailer? 2026 USPS Guide

Sending a bubble mailer with postage stamps is an easy and cost-effective way of shipping light, small packages. Not all bubble mailers can be sent with the same postage, though. Here is a step-by-step guide on when and how to put bubble mailer stamps on bubble mailers correctly.

Can You Put Stamps on a Bubble Mailer?

Yes, you can put stamps on a bubble mailer. Think of stamps as postage money. As long as the total stamp value covers the correct USPS postage, your bubble mailer can be accepted by the United States Postal Service (USPS).

But it is not as simple as putting one Forever Stamp on the mailer and sending it away. Bubble mailers almost always count as packages, not letters, once they contain products inside. That means they usually cost more to mail than a standard envelope.

It is worth calculating the correct postage before mailing, so your item does not get delayed, returned, or delivered with postage due.

We’ve developed Bubble Mailers that are in compliance with USPS requirements, making them ideal for sending with stamps while adequately protecting your items.

When to Use / Not Use Stamps to Ship a Bubble Mailer

Stamps are convenient, but they're not necessarily the best choice. Following is a convenient guide to help you make that choice.

Use stamps when:

• The bubble mailer is under 3/4 inch thick.
• It weighs 13 oz or less.
• It is still flexible, bendy, and uniformly thick.
• You are mailing small, soft, or flat items like papers, jewelry, lightweight accessories, or clothing.
• You do not need tracking.
• The total stamp value covers the correct USPS postage.

Avoid using stamps when:

• The mailer is rigid or contains bulky items.
• It exceeds the weight, thickness, flexibility, or shape limits for First-Class Mail large envelopes/flats.
• It needs tracking or proof of delivery, since stamps alone do not include tracking.
• It contains something valuable or urgent, where a USPS shipping label may be a better choice.
• It is more than 10 oz or more than 1/2 inch thick and you plan to drop it in a mailbox or collection box. USPS requires stamped mailpieces like this to be handed to a Post Office retail counter employee.
• You are sending it overseas, because international mail may require customs forms and more accurate postage handling.

USPS Services That Apply to Bubble Mailers

The bubble mailer you send through the mail will receive delivery service from one of the following USPS service categories.

• USPS Ground Advantage™: This service is the most common USPS option for bubble mailers that count as packages. It accepts packages up to 70 pounds and includes USPS Tracking when you buy a shipping label online or at the Post Office. USPS describes Ground Advantage as a domestic package service for items up to 70 lbs, with tracking included.

• First-Class Mail® (Large Envelope/Flat): A bubble mailer may qualify as a “flat” when it is flexible, rectangular, uniformly thick, and no more than 3/4 inch thick. In practice, many bubble mailers lose flat eligibility once products are placed inside. USPS states that large envelopes/flats are no thicker than 3/4 inch.

• Priority Mail®: If you need your package to arrive faster, Priority Mail is a good option. It costs more than Ground Advantage but includes tracking when you buy a USPS label. USPS lists Priority Mail as a 2–3 day service for packages up to 70 lbs.

• Media Mail®: Only for approved media and educational materials like books, printed music, manuscripts, and certain media. It should not be used for general merchandise. USPS defines Media Mail as an economy shipping solution for qualifying media items.

• Parcel Select®: This is generally more relevant for high-volume or commercial shipping, not typical stamp-based mailing by casual senders. USPS describes Parcel Select as a service with a 2–8 day delivery standard and destination-entry pricing for high-volume shippers.

How to Calculate Stamps for a Bubble Mailer?

Weigh It Accurately

Guessing the weight is one of the main reasons mail gets returned or arrives with postage due. Use a digital kitchen scale or postal scale for an accurate reading. Weigh the bubble mailer after it has been packed and sealed.

Tip: Picking a mailer with the right thickness will save on postage charges. For lightweight yet protective shipping options, check out JiaroPack’s 4x8 bubble mailers and 6x10 bubble mailers. Reliable USPS options for shipping smaller items like jewelry, gadgets, and documents.

Measure Thickness & Rigidity

The outcome of this phase will decide if your mailer qualifies as a “flat” or transforms into a “package”. Ask these questions:

• Is it more than 3/4 inch thick at any point?
• Is it rigid or difficult to bend?
• Is it lumpy or not uniformly thick?
• Does the item inside create an uneven surface?

If you answer “yes” to any of these, treat the bubble mailer as a package. Most bubble mailers with products inside fall into this group.

Pick the Correct USPS Category

Based on the step above, you will most likely ship your bubble mailer as a USPS Ground Advantage package. Do not try to send it as a letter or flat unless you have confirmed that it meets all flexibility, size, thickness, and uniformity standards.

Check the Current Rates

Postage rates can change, so always check the official USPS Price List Notice 123 or the USPS Postage Price Calculator before mailing.

For bubble mailers treated as packages, pay close attention to the USPS Ground Advantage price table. The final postage depends on weight, destination zone, and package size.

Do the Math or Use a Postage Calculator

One Forever Stamp covers $0.78 in postage as of April 2026. Examples

• If your bubble mailer qualifies as a flat and weighs 2 oz, the USPS flat price is $1.90, so you need stamps totaling at least $1.90.
• If your bubble mailer is treated as a parcel and weighs 6 oz, USPS Ground Advantage Retail uses the 8 oz price tier. From April 26, 2026 through January 17, 2027, that can range from $7.90 to $9.45, depending on the destination zone.
• If you use only Forever Stamps for a 6 oz parcel, you may need 11 to 13 Forever Stamps, depending on the actual USPS rate. In this case, buying a USPS label is usually cleaner and more practical.

For the easiest and most accurate method, use the official USPS Postage Price Calculator

How to Send a Bubble Mailer With Stamps?

Affix Stamps Correctly

• Place stamps in the upper right corner of the mailer.
• Make sure the stamps are flat, visible, and not overlapping.
• Use enough stamp value to cover the full postage.
• Keep the address area clear and easy to read.

Choose Drop-Off Method

Choose the drop-off method based on size, weight, and whether you are using stamps only.

• If the bubble mailer is 10 oz or less and no more than 1/2 inch thick, and it has enough postage, it may be deposited in a mailbox or USPS collection box.
• If the bubble mailer is more than 10 oz or more than 1/2 inch thick and bears only postage stamps, take it to a Post Office retail counter.
• If you need tracking, buy a USPS label online or at the Post Office instead of relying only on stamps.
• If you are unsure about the category or postage, hand it to a clerk and confirm before mailing.

Bubble Mailer Size Limits

Reference: USPS Price List Notice 123

Checklist Before You Mail

✅ Weigh your mailer after packing and sealing.

✅ Round up to the next ounce when calculating postage.

✅ Measure thickness and check flexibility.

✅ Decide whether it qualifies as a flat or must be treated as a parcel.

✅ Use the USPS Postage Price Calculator.

✅ Affix enough stamps to cover the full postage.

✅ Take stamped mail over 10 oz or over 1/2 inch thick to a Post Office counter.

✅ Buy a USPS label if you need tracking.

FAQs

How many stamps for a 6x9 bubble mailer?

There is no fixed number because postage depends on weight, thickness, flexibility, and destination.

If a 6x9 bubble mailer qualifies as a flat and weighs 1 oz, the USPS flat rate is $1.63, so it needs stamps totaling at least $1.63. If it contains goods and becomes a parcel, it will usually need USPS Ground Advantage postage, which costs more than flat mail.

How many stamps for a padded envelope?

A padded envelope is usually treated as a package once it contains items inside. The number of stamps depends on the final weight, destination zone, and USPS service. For most padded envelopes, use the USPS calculator or buy a USPS Ground Advantage label instead of guessing.

What happens if I don't put enough stamps on my bubble mailer?

USPS may return it to you for more postage or deliver it with a “Postage Due” notice, meaning the recipient may need to pay the difference. This can cause delays and create a poor delivery experience.

Can I just use one Forever Stamp?

Almost never. One Forever Stamp covers only $0.78 in postage as of April 2026. That is enough for a standard 1 oz letter, not a typical bubble mailer. A bubble mailer usually costs more because it is often treated as a flat or parcel.

Can I get a tracking number if I use stamps?

Stamps alone do not create a tracking number. Tracking requires a USPS barcode or shipping label. If you need tracking, buy postage online or at the Post Office.

Can I send international bubble mailers with stamps?

In some cases, yes, but international bubble mailers are more complicated. If the mailer contains goods, customs forms are usually required. For international shipments, it is safer to buy postage online or at a Post Office counter so the customs and postage requirements are handled correctly.

Conclusion

Mailing a bubble mailer with stamps is a valid option for light, low-value items when you do not need tracking. The key is to treat the mailer as what it actually is. If it is flexible, uniform, and thin enough, it may qualify as a flat. If it is thick, rigid, lumpy, or contains merchandise, it is usually a package.

Before mailing, weigh it, measure it, check the current USPS rate, and make sure your stamps cover the full cost. If the mailer is over 10 oz or over 1/2 inch thick and you are using only stamps, take it to a Post Office counter instead of dropping it in a mailbox.

Related reading:

1. Are Bubble Mailers Recyclable and How to Do It?
2. Bubble Mailer Weight Explained
3. USPS Bubble Mailer Rates Explained
4. Can You Ship Poly Mailers with Stamps?