Short answer: one standard Forever stamp usually covers about 3 to 5 sheets of regular paper.
But before you start counting pages and licking stamps, there’s an important detail most people miss. Stamps don’t care about the number of sheets. They care about weight.
A single Forever stamp covers:
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Up to 1 ounce of mail
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Sent as First-Class Mail
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Using standard letter size envelopes
Most regular printer paper weighs around 4 to 5 grams per sheet. That’s why 3 to 5 sheets usually stay under the 1 ounce limit. Once you go past that, you’ll need extra postage.
This question comes up a lot when people are mailing documents, school forms, or legal papers. And it’s closely related to how many stamps do I need, which depends entirely on how heavy the envelope ends up being.
Why Paper Weight Matters More Than Page Count
USPS doesn’t count pages. It weighs envelopes.
When you mail something, the post office places your envelope on a scale and checks whether it falls under the First-Class Mail postage rules for a standard letter. The magic number here is 1 ounce.
Different types of paper can throw your estimate off quickly. Thin printer paper is light, but thicker paper like resumes, certificates, or forms with heavy ink can push your envelope over the limit faster than expected.
Here’s what affects weight more than page count:
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Thicker paper stock
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Double-sided printing with heavy ink
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Extra items like photos or folded inserts
That’s why two envelopes with the same number of pages can require different postage. This is also why people often get confused and end up asking does one stamp cover multiple pages after their mail gets returned.
The safest approach is to think in ounces, not sheets.
How Many Sheets of Paper Equal 1 Ounce?
On average, 1 ounce equals about 4 sheets of standard printer paper.
This estimate assumes:
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Regular 20 lb printer paper
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A standard #10 envelope
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No extra inserts or thick materials
Here’s a simple breakdown most people can rely on:
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1 to 4 sheets → usually safe with one Forever stamp
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5 to 6 sheets → borderline, may need extra postage
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7+ sheets → almost always requires additional stamps
Once you cross the 1 ounce threshold, USPS charges extra for each additional ounce. That’s when people start searching for postage weight limits or wondering why their mail came back marked insufficient postage.
If you’re mailing anything important, the safest move is to weigh the envelope or ask the clerk to check it. Guessing works until it doesn’t.
What If You Use Double-Sided Printing or Thicker Paper?
Double-sided printing doesn’t change the number of sheets, but it absolutely affects weight.
Heavy ink coverage, especially on both sides of the paper, can push an envelope over 1 ounce faster than people expect. Thicker paper like resumes, certificates, or official forms also weighs more than standard printer paper.
If you’re using:
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Resume paper
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Cardstock
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Glossy paper
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Multiple inserts
You’ll likely need more than one stamp, even with fewer pages. This is a common reason mail gets returned and why people end up searching for insufficient postage explanations after the fact.
This is also where many people underestimate First-Class Mail postage because the envelope still “feels” light.
When in doubt, always assume thicker materials equal higher postage.
When Do You Need More Than One Stamp?
You need more than one stamp as soon as your envelope goes over 1 ounce.
For First-Class Mail, USPS charges extra for each additional ounce. That means once your letter crosses the weight limit, a single Forever stamp is no longer enough.
Here are some common situations where extra stamps are needed:
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More than 4 to 5 sheets of paper
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Thick or heavy paper types
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Double-sided printing with heavy ink
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Added items like photos or folded documents
A good rule of thumb is this: if your envelope feels noticeably thicker than a normal letter, it probably needs extra postage. This is why many people end up asking how many stamps do I need only after their mail comes back.
USPS won’t partially deliver underpaid mail. It either gets returned or arrives with postage due, which nobody enjoys.
Easy Ways to Avoid Underpaying Postage
The easiest way to avoid postage problems is to stop guessing.
If you’re mailing more than a couple of pages, here are some simple ways to make sure you’re covered.
First, weigh the envelope. A small kitchen scale works perfectly and removes all doubt. This instantly tells you whether you’re within postage weight limits or need extra stamps.
Second, take it to the post office. A USPS clerk can weigh it in seconds and tell you exactly how much postage you need. This is especially helpful if the mail is important or time sensitive.
Third, when in doubt, add extra postage. Overpaying by a few cents is better than dealing with returned mail or delays. Many people learn this the hard way after dealing with insufficient postage issues.
Lastly, remember that Forever stamps only cover the first ounce. Anything beyond that requires additional postage, even if the envelope looks small.
Final Answer: How Many Sheets of Paper Per Stamp?
For most standard letters, one Forever stamp covers about 3 to 5 sheets of regular paper.
The exact number depends on weight, not page count. As long as your envelope stays under 1 ounce and follows First-Class Mail postage rules, one stamp is usually enough.
Once you go past that limit, you’ll need extra postage. Thicker paper, heavy ink, or extra inserts can push you over the edge faster than expected.
If you remember one thing, remember this: USPS charges by weight, not by how many pages you include.
When in doubt, weigh the envelope or add extra postage and avoid the hassle altogether.