Ever stood at the post office counter with a stack of thick envelopes, feeling that slight pang of anxiety as the clerk slides them onto the scale? We’ve all been there. You have your Forever stamps ready to go, but then you realize the envelope is a bit too chunky. It’s over that one-ounce limit. Now what? Honestly, the math should be simple, but the U.S. Postal Service (USPS) changes things just often enough to keep us guessing.
If you are looking for the quick answer: The current price for an additional ounce stamp is $0.29.
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That's the rate as of early 2026. While shipping services like Priority Mail saw some price hikes this January, the Postmaster General decided to hold steady on First-Class Mail for the beginning of this year. So, for now, your 1-ounce letter stays at $0.78 and that extra weight costs you twenty-nine cents.
How Much Is the Additional Ounce Stamp Right Now?
It’s easy to get confused because "stamps" aren't just one thing anymore. You’ve got your standard Forever stamps, but then you have these specific Additional Ounce stamps. They usually feature something cute—right now, the "School Bus" design is the go-to.
Basically, if your letter weighs more than 1 ounce but less than 3.5 ounces, you don't need to slap two $0.78 Forever stamps on it. That would be a waste of money. Instead, you use one Forever stamp for the first ounce and then add a $0.29 additional ounce stamp for every ounce after that.
The Breakdown of Letter Costs
Let's look at how this actually hits your wallet when you're mailing something a bit heavier than a standard birthday card:
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A 2-ounce letter will set you back $1.07. That is your $0.78 base plus the $0.29 extra.
If you’re pushing 3 ounces, you’re looking at **$1.36**.
Once you hit 3.5 ounces, which is the limit for a standard envelope, the price is $1.65.
If it weighs more than 3.5 ounces? Well, the post office stops calling it a "letter" and starts calling it a "flat" or a "large envelope." That's a whole different pricing tier.
Why the Price Stayed at 29 Cents in 2026
You might have heard the news about USPS raising rates again in January 2026. It’s true, but there's a catch. The Postal Service is currently split into two worlds: "Market Dominant" products and "Competitive" products.
Postmaster General David Steiner made the call to keep First-Class Mail—which includes our 1-ounce stamps and those additional ounce add-ons—at the July 2025 levels. They’re trying to balance the books without making it impossible for people to send a letter. Meanwhile, if you’re shipping a package via Ground Advantage or Priority Mail, you did see a price jump this month (around 6% to 7.8% on average).
It's sorta interesting. USPS is under huge pressure to reach financial stability under the "Delivering for America" plan. They’ve been hiking prices twice a year lately. While we caught a break this January on letter stamps, most experts expect the next round of increases for the additional ounce stamp to land somewhere around mid-2026.
Common Mistakes with Heavy Envelopes
Most people overpay. Seriously.
I see it all the time. Someone has a wedding invitation that’s a little heavy. They aren't sure of the weight, so they just put two Forever stamps on it. If that letter is 2 ounces, you just paid $1.56 for a $1.07 job. You essentially gave the government a 49-cent tip.
Then there’s the "non-machinable" trap. If your envelope is square, or if it’s stiff and doesn’t bend, or if it has a weird clasp on the back, the USPS hits you with a surcharge. It doesn't matter if it weighs less than an ounce. That "non-machinable" fee is also $0.29. So, a square invitation usually costs the same as a 2-ounce letter ($1.07).
Knowing Your Limits
- The 3.5 Ounce Wall: This is the hard limit for letters. If your envelope is 4 ounces, it must be sent as a Large Envelope (Flat), which starts at $1.63 for the first ounce.
- The Thickness Factor: If your letter is more than 1/4 inch thick, it’s not a letter anymore. It’s a flat.
- The "Metered" Discount: If you use a postage meter for a business, you actually pay a bit less—$0.74 for the first ounce instead of $0.78. But the additional ounce price usually stays the same at $0.29.
Where to Buy Them Without the Wait
Honestly, the easiest way to get these is just to buy a sheet of 20 at the post office or on the USPS website. They are called "Additional Ounce" stamps and they don't have a dollar amount printed on them. Like Forever stamps, they are "valid for the value at the time of mailing."
This means if you buy a bunch of $0.29 cent stamps now, and the price goes up to $0.32 in August, your old stamps are still good for that second ounce. They essentially "lock in" the additional ounce rate.
You can also find them at some grocery stores or pharmacies, though they usually only stock the standard Forever stamps. If you're in a pinch and only have Forever stamps, you can use one and then add $0.29 worth of smaller "cent" stamps (like the 1, 2, 5, or 10-cent ones they sell), but your envelope is going to look like a collage by the time you're done.
Practical Steps for Your Next Mailing
If you’re preparing a large mailing—like holiday cards with inserts or business contracts—don't guess the weight. Use a small digital kitchen scale. One or two extra sheets of paper can easily push you from 0.9 ounces to 1.1 ounces.
To handle your postage correctly today:
- Weigh your envelope. If it's 1.1 ounces, you need that extra postage.
- Check the shape. If it's square or lumpy, add $0.29 regardless of weight.
- If you have older stamps, check the current value at the USPS Postal Explorer website to make sure you aren't underpaying.
- Keep a book of "Additional Ounce" stamps in your desk; they are much cheaper to use as "top-ups" than using two full-price Forever stamps.
The current 29-cent rate is expected to hold until at least July 2026, so stocking up now isn't a bad idea if you send a lot of heavy mail.