Do I need a stamp to mail a letter?

You need a stamp when you mail the physical envelope yourself. You do not need to buy a separate stamp when an online print-and-mail service prepares and mails the letter for you.

As of May 31, 2026, USPS lists a First-Class Mail Forever stamp at $0.78 for a 1-ounce domestic letter. USPS has also filed planned July 12, 2026 price changes that would increase the 1-ounce letter price to $0.82 if favorably reviewed.

USPS rates change, so the safest answer for a DIY envelope is to check the USPS price page or calculator before mailing.

For a normal U.S. letter, start with weight and shape. A Forever stamp covers the first ounce of a standard rectangular First-Class letter. Add postage when the letter is heavier, unusually shaped, rigid, lumpy, square, vertical, or needs an extra USPS service.

If you are not sure, weigh the sealed envelope and use the USPS price calculator before dropping it in the mail. If you use PostalForm, upload or write the letter online instead; the checkout quote includes postage in the full print-and-mail price.

One current First-Class Mail Forever stamp is usually enough when all of these are true:

• The letter is going to a U.S. address.
• The envelope is a standard rectangular letter envelope.
• The total weight is 1 ounce or less.
• The envelope is not rigid, lumpy, square, vertical, or closed with clasps, string, or buttons.
• You do not need Certified Mail, insurance, Return Receipt, or another extra service.

USPS says a 1-ounce letter is roughly four sheets of regular printer paper in a business-sized envelope. If you use thicker paper, many pages, inserts, labels, cards, or anything that changes the envelope shape, weigh it before mailing.

A stamp pays postage; it does not create tracking, delivery confirmation, or a signature record for an ordinary First-Class letter. USPS says tracking is not available for First-Class Mail letters unless you add another service. Use Certified Mail, Return Receipt, Registered Mail, Priority Mail, or Priority Mail Express when proof matters.

For bills, disputes, legal notices, forms, and deadline-driven packets, decide whether you only need postage or also need a mailing record. PostalForm can show available proof options at checkout for qualifying mail.

You may need more postage when:

• The letter weighs more than 1 ounce.
• The mailpiece is a large envelope or flat.
• The envelope is square, rigid, lumpy, vertical, or unusually shaped.
• You are mailing internationally.
• You want Certified Mail, Return Receipt, insurance, signature proof, or another add-on.
• You are mailing something that USPS treats as a package instead of a letter.

If the envelope exceeds First-Class letter limits, USPS may price it as a flat or package instead of a simple letter. That is why shape and thickness matter, not just page count.

If a letter has no postage or not enough postage, USPS may return it to the sender, delay it, or deliver it with postage due. If there is no return address, the mailpiece is harder to resolve and may not reach the recipient.

Use a complete return address, especially for bills, legal notices, forms, disputes, and deadline-driven mail.

You do not have to keep stamps at home if you are willing to use another postage method.

For ordinary letters, PostalForm is the simplest route when you do not have a printer, envelopes, stamps, or time for a post office errand. Start with send a letter online or mail a PDF online.

For a normal envelope, USPS says the stamp goes in the upper-right corner. The return address goes in the upper-left corner, and the delivery address goes near the center of the envelope.

If you use PostalForm, you do not place a stamp yourself. You provide the sender and recipient addresses online, then PostalForm prepares the mailpiece.

• USPS First-Class Mail
• USPS How to Send a Letter or Postcard
• USPS Notice 123 price list
• USPS planned July 12, 2026 price changes