Industry Trends

Where to Put a Second Stamp on an Envelope (And When You Even Need One)

Put the second stamp in the upper right corner, next to the first one. That's the only place USPS accepts it.

I'm the guy who handles our company's direct mail and shipping for about 500 orders a month. I've personally made (and documented) 12 significant postage mistakes, totaling roughly $870 in wasted budget—mostly from returned mail and late fees. Now I maintain our team's checklist to prevent others from repeating my errors. The rule above is the single biggest time-saver on that list.

If you're in a hurry, that's all you need. Stick the extra stamp(s) right next to the first in the top right corner, and you're done. The rest of this is why that's the rule, the sneaky exceptions, and how to know if you even need that second stamp in the first place.

Why This Rule Exists (And My Costly Lesson)

This isn't about aesthetics; it's about USPS automation. Their sorting machines are designed to look for postage in one specific spot. Sticking a stamp somewhere "creative"—like the back flap or the lower left corner—means your mail might get kicked out for manual processing, which adds days, or worse, get returned for insufficient postage.

In my first year (2019), I made the classic "stamp on the back" mistake with a batch of 250 handyman flyers. I thought it looked cleaner. The result? About 40 of them came back a week later stamped "RETURN TO SENDER - POSTAGE DUE." That was $28 in wasted stamps plus a week's delay on a time-sensitive promotion. The lesson was brutal: machines don't appreciate design choices.

According to USPS (usps.com), as of January 2025, a standard 1-ounce First-Class Mail letter costs $0.73. A large envelope (or "flat") starts at $1.50 for the first ounce. The key is knowing the weight and shape before you start sticking. Every spreadsheet analysis for our flyers pointed to using large envelopes for better visibility. My gut said standard envelopes were cheaper and fine. I went with the data for a 5,000-piece order. Turns out my gut was right about the cost, but wrong about the thickness—many got surcharged as flats. We've caught 47 potential weight/size errors using a simple pre-check list in the past 18 months.

When You Actually Need a Second Stamp

This is where most people overpay. You don't need a second stamp just because your envelope feels heavy. You need it based on weight and dimensions.

• Standard Letter (up to 6.125" x 11.5" x 0.25" thick): First stamp covers 1 oz ($0.73). Add $0.28 for each additional ounce. So, for a 2 oz letter, you need $1.01 in postage. That's one Forever stamp ($0.73) plus one "Additional Ounce" stamp ($0.28), or two Forever stamps ($1.46—which means you're overpaying by $0.45).
• Large Envelope/Flat (over 6.125" x 11.5" up to 12" x 15" x 0.75" thick): This is a different price tier. First ounce is $1.50. Each additional ounce is $0.28. So a 2 oz flat needs $1.78 in postage. You can't use just two Forever stamps ($1.46); you'd be short. You'd need specific stamp denominations.

Looking back, I should have bought a roll of "Additional Ounce" stamps for our bulk mailings. At the time, I thought using extra Forever stamps was simpler. It was simpler, all right—simpler to waste money.

The "Handyman Flyer" Exception & Business Credit Card Tricks

Here's a real-world wrinkle. Let's say you're designing handyman flyer ideas and plan to mail them. If your flyer is a standard letter size but rigid (like some cardstock), it might be considered a "non-machinable" letter. USPS charges an extra $0.44 surcharge for those. So your 1 oz rigid flyer needs $1.17 in postage, not $0.73. That's where a Forever stamp plus a Non-Machinable Surcharge stamp (or equivalent postage) comes in.

Now, for the business credit card rewards accounting tie-in (this is the efficiency angle). If you're doing any volume of mailing, buy your postage online through USPS.com or a service like Stamps.com. You can print exact postage (so no overpaying with extra Forever stamps), and you can often pay with a business credit card. That turns a necessary expense into potential rewards points or cash back. Just make sure your accounting method tracks this shipping spend separately—it's often a deductible business expense. The automated process eliminated the data entry errors we used to have when manually logging stamp purchases.

What About EcoEnclose Packaging and Free Shipping?

This postage logic applies to your outbound customer mail too. If you're an e-commerce brand using EcoEnclose mailers (which are great, by the way—100% recycled content and specialized for e-commerce), you need to know if your mailer is a "letter" or a "flat." Many of their eco-friendly mailers, once filled, will bump into the "flat" size or thickness category.

When you offer EcoEnclose free shipping, you're absorbing this cost. Knowing the exact postage means you're not overestimating (and cutting into your margins) or underestimating (and eating unexpected costs). The value of getting this right isn't just the stamp cost—it's the certainty. For customer orders, knowing the correct postage guarantees delivery without your customer facing a "postage due" slip, which is a surefire way to lose a repeat buyer.

Boundary Conditions: When This Advice Doesn't Apply

To be fair, this whole "second stamp" discussion is for First-Class Mail. If you're sending a thick catalog or a heavy sample using Priority Mail, you'll use a completely different label or postage system. Also, this is for the U.S. domestic mail. International postage is a whole other ballgame with its own stamps and rules.

And granted, for a one-off personal letter, slapping on two Forever stamps is fine—you're paying for convenience. But for a business, where mailings are repeated, that overpayment adds up fast. I get why people do it—budgets are real and time is short. But the hidden costs of wrong postage (returns, delays, customer service issues) add up.

Finally, a note on mailboxes: under federal law (18 U.S. Code § 1708), only USPS-authorized mail may be placed in residential mailboxes. So if you're doing a local flyer drop for your handyman business, you can't just stick unstamped flyers in mailboxes. That's a quick way to a fine. Door hangers or community boards are the way to go.

There's something satisfying about nailing the postage. After all the confusion and wasted money, seeing a batch of mail go out smoothly, with the right stamps in the right corner, and none of it coming back—that's the small, operational payoff that makes my job easier.