Can You Use Stamps on a Package? The 2026 USPS Rules

You have a small box, a sheet of Forever stamps, and a blue collection box on the corner. Can you just stick on enough stamps and drop it in? The answer is yes — with two conditions that almost no online guide gets right, and one of them has changed since the rule everyone remembers was written.

USPS explicitly allows postage stamps as payment for First-Class Mail and USPS Ground Advantage – Retail. What trips people up is not whether stamps are legal on a package, but how much value you must apply and where you are allowed to hand the piece over. Below is the current Domestic Mail Manual version, the real prices from Notice 123, and the stamp-by-stamp math.

The Short Answer

DMM 134.1.1 states that postage for single-piece First-Class Mail and USPS Ground Advantage – Retail must be paid with affixed postage stamps, postage evidencing system postage, or precanceled stamps, and that Ground Advantage – Retail may additionally be paid through Click-N-Ship. DMM 134.1.2 adds the obvious-but-critical part: in a postage-affixed mailing, you must apply enough value in adhesive stamps to equal the postage required, including any surcharges.

So stamps are valid postage on a package. But there is a widespread claim that a stamped parcel can go in a collection box as long as it weighs 13 ounces or less. That “13-ounce rule” comes from a 2009 DMM revision that took effect in January 2010. It is no longer the current threshold. The rule in force today — DMM 136.1.0, revised July 12, 2026 — uses 10 ounces and half an inch of thickness, and thickness is the part that catches almost everyone.

The Real Drop-Off Rule: 10 Ounces or Half an Inch

DMM 136.1.0 says that First-Class Mail (letters, cards, flats) and USPS Ground Advantage – Retail items may be deposited in any collection box, mail receptacle, or place where mail is accepted if the full postage is paid with stamps — except for items bearing only postage stamps that weigh more than 10 ounces or measure more than one half-inch in thickness. Those items may not go in a collection box, be picked up during normal delivery, or be taken through Pickup on Demand. The sender must present them to an employee at a Post Office.

Your stamped item	Collection box / carrier / Pickup on Demand?	Where it must go
≤ 10 oz and ≤ ½” thick	Yes	Any collection box, mailbox, or Post Office
> 10 oz (any thickness)	No	Present to a USPS employee at a Post Office
> ½” thick (any weight)	No	Present to a USPS employee at a Post Office
Any piece with a customs form, paid with stamps	No	Retail service counter (DMM 703.2.5.2)

Read that third row again. A padded bubble mailer is typically ¾ inch to 1 inch thick once it is filled. It can weigh three ounces — far under 10 ounces — and still be barred from a blue box because of thickness alone. Nearly every “just drop it in the box” tip online omits this. USPS returns improperly presented items to the sender for proper deposit, which costs you a week and a trip to the counter anyway.

The same 10-ounce / half-inch limit applies to Priority Mail pieces paid only with stamps under DMM 126.1.2. If you are mailing an APO, FPO, or DPO military package, note the additional customs-form counter requirement described there.

What It Actually Costs: Flat Prices vs. Parcel Prices

Here is the part that can save you real money. Under DMM 133.1.1, the USPS Ground Advantage – Retail parcel price applies to parcel-size pieces, and also to flat-size pieces that fail the flat standards — anything over 15 inches long, 12 inches high, or ¾ inch thick, or that is rigid, nonrectangular, or lumpy. A flexible, uniformly thick padded envelope that stays under those limits is still a flat, and flats are priced per ounce, not by zone.

These are the Notice 123 retail prices effective October 4, 2026 (the Ground Advantage figures are time-limited peak-season prices scheduled to run through January 17, 2027):

Weight	First-Class flat (anywhere in the U.S.)	Ground Advantage – Retail parcel, Zone 1	Ground Advantage – Retail parcel, Zone 5
1 oz	$1.69	—	—
4 oz	$2.56	$8.40	$9.35
8 oz	$3.72	$8.40	$9.35
12 oz	$4.93	$10.05	$11.70
13 oz	$5.24	$10.05	$11.70

At 8 ounces, the difference between a qualifying flat and a parcel is roughly $4.70 to $5.60 — before you even account for cross-country zones, where Ground Advantage climbs to $10.20 or more at the lightest weights. The practical move for small, soft goods is to keep the mailer flexible, uniformly thick, and under ¾ inch so it stays a flat. If it is rigid, lumpy, or box-shaped, it is a parcel and the Ground Advantage table applies. Our envelope sizes and postage guide walks through the exact dimensions.

One more cost that is easy to miss: letter-size pieces with square, rigid, or clasp-style construction are hit with the $0.49 nonmachinable surcharge. That applies on top of the letter price, not instead of it — see the nonmachinable surcharge explained.

How Many Forever Stamps Do You Need?

A Forever stamp is worth the current 1-ounce stamped letter price — $0.82 as of October 4, 2026. Divide the required postage by $0.82 and round up, then make up the difference with small-denomination stamps. USPS sells regular stamps in 1¢, 2¢, 3¢, 4¢, 5¢, 10¢, and 40¢ denominations, so exact payment is possible if you keep a few on hand.

Mailpiece	Postage due	Simplest stamp combination
1 oz letter	$0.82	1 Forever stamp
2 oz letter	$1.11	1 Forever + one 29¢ additional-ounce stamp
1 oz flat	$1.69	2 Forever + one 5¢ stamp
4 oz flat	$2.56	3 Forever + one 10¢ stamp ($2.56 exact)
8 oz flat	$3.72	4 Forever + one 40¢ + one 4¢ stamp ($3.72 exact)
13 oz flat	$5.24	6 Forever + three 10¢ + one 2¢ stamp ($5.24 exact)
4 oz parcel, Zone 1	$8.40	10 Forever + two 10¢ stamps ($8.40 exact)

Two cautions. First, round up on weight: First-Class Mail charges by the ounce or fraction of an ounce, and Ground Advantage rounds up to 4 oz, 8 oz, 12 oz, or 15.999 oz. A 4.1-ounce parcel is billed as 8 ounces. Second, do not guess on the total. Underpaying does not get your package delivered with a bill at the other end — see what happens if you underpay postage. For the full letter-weight conversion table, use our how many Forever stamps guide.

When Stamps Are the Wrong Choice

• You need tracking. Ground Advantage includes USPS Tracking when you buy a printed label, but a pile of stamps on a box produces no tracking number. If delivery confirmation matters, print a Click-N-Ship label or pay at the counter.
• You need insurance. Label-purchased Ground Advantage includes $100 of insurance. Stamps alone do not give you a claim to file.
• The piece is over 10 ounces or over half an inch thick. You already have to visit a Post Office, so let the clerk print a proper label and barcode.
• You are mailing internationally. Customs declarations, country restrictions, and the customs-form counter rule make stamps impractical. Military APO/FPO/DPO mail is the exception, as explained in our military mail guide.
• You are shipping anything valuable or time-critical. Registered Mail, Certified Mail, and Priority Mail Express all require counter transactions with forms that stamps cannot replace.

Step-by-Step: Mailing a Small Package With Stamps

1. Weigh and measure the finished, sealed package — including the padding and any inserts.
2. Classify it. Flexible, rectangular, uniformly thick, and under 15″ × 12″ × ¾” = a flat. Otherwise it is a parcel priced as Ground Advantage – Retail.
3. Look up the price in the current Notice 123 retail table, and add the $0.49 nonmachinable surcharge if it applies.
4. Apply stamp value equal to the full amount. Use small-denomination stamps to hit the exact figure instead of overpaying with a whole Forever stamp.
5. Place stamps in the upper-right corner of the address side, clear of seams and edges. If several stamps are needed, our guide to where to place multiple stamps shows the layout USPS machines expect.
6. Decide where to deposit it. Only stamped pieces at or under 10 oz and ½ inch thick can go in a collection box. Anything heavier or thicker goes to a Post Office employee.
7. Add a return address — required for parcels and strongly advised for everything else.

Frequently Asked Questions

Can I put Forever stamps on a package?

Yes. DMM 134.1.1 permits affixed postage stamps for single-piece First-Class Mail and USPS Ground Advantage – Retail. You must apply enough stamp value to cover the full postage including any surcharges.

Is there still a 13-ounce rule for stamped mail?

No. The 13-ounce threshold came from a 2009 revision effective January 4, 2010. The current rule, DMM 136.1.0 (revised July 12, 2026), uses 10 ounces or more than half an inch of thickness — whichever applies first. Guides that quote 13 ounces are out of date.

Can I drop a stamped bubble mailer in a blue collection box?

Usually not. A filled padded mailer is commonly ¾ inch to 1 inch thick, which exceeds the half-inch limit even if it weighs only three ounces. Take it to a Post Office and hand it to an employee.

How many Forever stamps for a 4-ounce package?

It depends on the shape. A qualifying flat costs $2.56 — three Forever stamps plus a 10¢ stamp. A parcel priced as Ground Advantage – Retail starts at $8.40 in Zone 1, which is ten Forever stamps plus two 10¢ stamps. That gap is why the flat-vs-parcel classification matters more than the weight.

Do stamps give me tracking on a package?

No. USPS Tracking comes with a printed Ground Advantage label. Stamps alone do not generate a tracking number, so use Click-N-Ship or a counter transaction if you need delivery confirmation or insurance.

What happens if I put a stamped 1-pound box in a collection box?

DMM 136.1.0 says improperly presented stamped items are returned to the sender for proper deposit. Expect it to come back to you rather than continue to its destination — and re-check the postage, because a 1-pound Ground Advantage parcel is priced by the pound, not by the ounce.

Can I use old stamps to make up exact postage?

Yes, as long as they are genuine, unused, and valid U.S. postage. Nondenominated Forever stamps are worth the current 1-ounce rate regardless of when you bought them; denominated stamps count at face value. See can you use old postage stamps for the details.

Keep a Few Small Denominations on Hand

The single most useful thing for anyone mailing small packages with stamps is a handful of 1¢, 5¢, 10¢, and 40¢ stamps — they let you hit an odd postage total exactly instead of throwing away a whole extra Forever stamp. For letters, cards, and lightweight flats, one Forever stamp still does most of the work; stock up in the wholesale Forever stamp category, where per-piece cost drops as low as 15 cents, or browse holiday stamps before the December 17 domestic deadline. Our bulk-buying guide has the quantity breakpoints.