How many stamps do I need for a large envelope?

A 1 oz large envelope (such as a 9×12) costs $1.63, which is 3 Forever stamps. Add roughly one Forever stamp for each additional 2 oz.

How many stamps for a letter?

A standard letter up to 1 oz needs a single Forever stamp ($0.78). A 2 oz letter needs 2 stamps ($1.07).

How many stamps do I need for a 1.5 oz letter?

USPS rounds partial ounces up, so a 1.5 oz letter is charged at the 2 oz rate — 2 Forever stamps ($1.07).

What happens if I don’t use enough stamps?

USPS may return the item for more postage or deliver it “postage due,” asking the recipient to pay the difference. When unsure, add one more Forever stamp.

Can I mail a letter online without stamps?

Yes. Online postage services let you weigh, print, and pay exact postage at home, so you never have to guess how many stamps to use.

How many stamps do I need? ✉️

Enter the weight to see the exact USPS postage and how many Forever stamps it takes — for letters and large envelopes — plus Priority, FedEx, and UPS rates side by side.

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Calculate exact envelope postage

Type the origin and destination city.
Select location from autocomplete.
Enter the envelope weight.
Click "Get rates" to compare envelope rates from USPS, FedEx, and UPS.

This site compares shipping rates from postage purchased online.

Purchasing postage from a physical USPS, UPS, or FedEx store will not be the discounted rates shown on this site.

See our shipping discounts page for accounts that provide discounted rates, or learn how to buy shipping labels online.

How many stamps do I need?

A standard letter up to 1 oz needs 1 Forever stamp ($0.78).
A 2 oz letter needs 2 Forever stamps ($1.07).
A 1 oz large envelope (9×12) needs 3 Forever stamps ($1.63).

Heads up: USPS postage is set to rise on July 12, 2026 — the Forever stamp goes from 78¢ to 82¢ (pending final approval). See the schedule →

Stamps by letter weight

First-Class Mail letters, up to 3.5 oz.

Weight	Forever stamps	Postage
1 oz or less	1	$0.78
1.1–2 oz	2	$1.07
2.1–3 oz	2	$1.36
3.1–3.5 oz (max)	3	$1.65

Stamps for a large envelope (9×12 / flats)

Weight	Forever stamps	Postage
1 oz or less	3	$1.63
1.1–2 oz	3	$1.90
2.1–3 oz	3	$2.17
3.1–4 oz	4	$2.44

Forever stamp value: $0.78. Prices read live from our USPS pricing database and update when rates change.

Prefer physical stamps? Work out the combo

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Skip stamps — print a label instead

Printing postage online is the easy alternative to stamps:

Pay exact postage — no overpaying or stacking stamps to cover the weight
No handwriting — type the address once and print a clean label
Skip the line at the post office — drop it in any mailbox or schedule a free pickup
Discounted rates you can’t get buying stamps at the counter

Print postage with Stamps.com →

Special situations

Large or 9×12 envelopes

Anything bigger than 11½ × 6⅛ inches mails at the large-envelope (flat) rate, which starts higher than a letter. See the table above, or use the calculator for the exact figure by weight.

Non-machinable letters (square, rigid, or lumpy)

Square envelopes, invitations, and stiff or bulky mail add a non-machinable surcharge (about $0.49) on top of the letter rate.

International letters

A letter to another country needs a Global Forever stamp (about $1.70). For the step-by-step, see how to mail a letter.

Certified mail

Certified Mail adds a service fee on top of postage and gives you proof of mailing and delivery — useful for legal or time-sensitive documents.

Stamp FAQs

How many stamps do I need for a large envelope?: A 1 oz large envelope (such as a 9×12) costs $1.63, which is 3 Forever stamps. Add roughly one Forever stamp for each additional 2 oz.
How many stamps for a letter?: A standard letter up to 1 oz needs a single Forever stamp ($0.78). A 2 oz letter needs 2 stamps ($1.07).
How many stamps do I need for a 1.5 oz letter?: USPS rounds partial ounces up, so a 1.5 oz letter is charged at the 2 oz rate — 2 Forever stamps ($1.07).
What happens if I don’t use enough stamps?: USPS may return the item for more postage or deliver it “postage due,” asking the recipient to pay the difference. When unsure, add one more Forever stamp.
Can I mail a letter online without stamps?: Yes. Online postage services let you weigh, print, and pay exact postage at home, so you never have to guess how many stamps to use.