How Many Stamps Do I Need for a Letter? (Full Guide)

If there’s one thing that’s certain about the United States Postal Service, it’s that something is always changing.

Dealing with constant changes can be frustrating and confusing, especially if you want to know something as simple as how many stamps you need to mail a letter.

Luckily, we’ve put together a guide to help you navigate USPS postage, so keep reading to learn more!

How Many Stamps Do I Need for a Letter In 2024?

Standard-sized letters weighing less than 1 ounce are sent using First-Class Mail service, and require one Forever Stamp for mailing in 2024. Forever Stamps change in value, depending on the First-Class postage rate. Irregularly-shaped letters, or those weighing more than 2 ounces require more postage, such as additional ounce and extra cent stamps.

There’s a lot more to know when it comes to determining how many stamps your letter needs, so make sure to read our guide for more useful facts and tips!

How Many Stamps Do I Need for a Standard-Size Letter?

Before answering this question, it’s important to know what USPS considers a standard-sized letter to be.

USPS defines a standard-sized letter as one that meets the following criteria:

  • Rectangular
  • At least 3 ½ inches x 5 inches x 0.0007 inches thick
  • No more than 6 ⅛ inches x 11 ½ inches by ¼ inches thick

Envelopes falling within these guidelines are classified as letters, and are subject to First-Class Letter rates.

First-Class Letter rates change frequently.

However, one Forever Stamp will always cover the postage price of a standard-sized letter, weighing less than 1 ounce, regardless of when you bought the stamp.

These size guidelines can seem pretty precise and overwhelming, but don’t worry too much.

If you’re sending a greeting card or a legal-sized envelope, you can be almost certain that one Forever Stamp will cover the postage.

However, if you have any questions, feel free to take your envelope to the post office for confirmation.

How Many Stamps Do I Need for Square Cards?

Some greeting cards, such as those that are square-shaped, do not meet the requirements to be mailed as regular First-Class letters.

Because of their unique shape, these cards cannot be sorted by USPS’ machines. Rather, USPS employees must sort them by hand and cancel the stamps manually.

As a result of these extra steps, USPS imposes a non-machinable surcharge of $0.17 on top of the First-Class postage.

If your card is considered non-machinable, USPS recommends purchasing a non-machinable stamp to cover the additional postage.

This stamp covers both regular postage and the surcharge.

Like Forever Stamps, non-machinable stamps will always cover the surcharge, even if rates increase in the future.

Other cards that require a non-machinable stamp include the following:

  • Contain odd-shaped contents like loose keys, coins, or tokens that cause an uneven thickness
  • Items that are enclosed in any plastic material.
  • Items with closures made from clasps, strings, or buttons.

How Do You Know How Many Stamps to Put on a Letter?

How Do You Know How Many Stamps to Put on a Letter? USPS

As mentioned above, if you’ve got a standard-sized envelope or greeting card that weighs less than 1 ounce, then one Forever Stamp is all you’ll need to cover postage.

If you have a square greeting card, or one with special elements that increase the weight, check the back of the card for a butterfly icon.

Since 2010, USPS and the American Greeting Card Association have collaborated to make it easier for consumers to know when extra postage is required.

As a result of this effort, all USPS’ non-machinable stamps have butterflies on them, while most non-machineable greeting cards will carry a butterfly icon.

To determine the number of stamps required for heavier letters, weigh your item using a sensitive kitchen or mail scale (i.e. one that can measure in ounces).

Plug the weight into USPS’ Postage Price Calculator, choose First-Class mail service, and see how much you’ll need to pay.

From there, divide the total postage cost by the current price of a Forever Stamp. This will tell you how many Forever Stamps you’ll need to cover postage.

Alternatively, you can purchase denominational stamps (e.g. 1 cent, 2 cents, 5 cents) to make up the difference in postage.

If you don’t have access to a scale, take your letter to the post office, and have an employee tell you how much postage you owe.

From there, you can add stamps you’ve already purchased, or pay for the postage, and have the employee print it for you.

Do I Need 2 Stamps for One Letter?

You’re required to pay extra postage if the letter you’re mailing weighs more than 1 ounce and/or is irregularly shaped.

You can pay for this additional postage by adding additional stamps to your envelope, however, this may result in overpaying for postage.

For this reason, USPS recommends not putting 2 Forever Stamps on heavier mail. 

Instead, purchase additional ounce stamps to cover letters weighing more than 1 ounce. In most cases, this is cheaper than adding 2 Forever Stamps. 

However, if you’re putting 2 stamps on an envelope, make sure they don’t overlap.

How Many Stamps Do I Need for a 2 Ounce Letter?

Letters weighing between 1.1 and 2 ounces require one 2-ounce Forever Stamp. USPS currently sells these stamps for $0.78.

Like Forever Stamps, these stamps hold their value, regardless of any postage rate increases. In other words, this stamp will always cover postage for letters weighing up to 2 ounces.

How Many Stamps Do I Need to Send a Letter Out of State?

If you’re mailing a standard-sized letter weighing 1 ounce or less from the United States to another state, you will need 1 Forever Stamp.

In other words, it doesn’t matter if you’re mailing a letter to the next state over or all the way to Alaska—the rate stays the same.

This is also true when sending letters to U.S. territories (e.g. U.S. Virgin Islands, Puerto Rico, or Guam) and to APO, FPO or DPO addresses overseas.

Even though these destinations are technically “abroad,” USPS treats them as domestic addresses and the required postage reflects this.

How Many Stamps Do I Need to Send a Letter to Canada?

Currently, USPS charges $1.30 for First-Class letters sent to Canada. This covers letters weighing up to 2 ounces.

You can cover this postage by purchasing 1 Global Forever Stamp.

Like domestic Forever Stamps, Global Forever Stamps keep their value, and will always cover postage to Canada, as long as your letter weighs 2 ounces or less.

While Global Forever Stamps are the easiest way to cover postage to Canada, you can also pay using a combination of domestic Forever Stamps and/or extra cent stamps.

How Many Stamps Do I Need to Send a Letter to Mexico?

USPS charges $1.30 for First-Class letters sent from the United States to Mexico. This amount covers letters weighing up to 1 ounce.

You can cover this amount of postage by purchasing 1 Global Forever stamp.

Letters weighing between 1.1 and 2 ounces currently cost $1.96.

How Many Stamps Do I Need to Send a Letter to Australia?

A 1-ounce letter going to Australia costs $1.30, and postage can be paid for using 1 Global Forever stamp.

Letters weighing more than 1 ounce but less than 2 ounces cost $2.25.

How Many Stamps Do I Need to Send a Letter to England?

One Global Forever stamp will cover the cost of postage for a 1-ounce letter going to England. However, heavier letters cost $2.43.

If you are looking to learn more, you can also see our posts on 14 USPS stamp types, do USPS stamps expire, and Purple Heart Forever stamps.


When you’re trying to figure out how many stamps you need to mail your letter, you’ll need to take the letter’s size, shape, weight, and destination into consideration.

In most cases, you can find the information you need online. However, if you’re ever in doubt, bring your letter to the post office.

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Marques Thomas

Marques Thomas graduated with a MBA in 2011. Since then, Marques has worked in the retail and consumer service industry as a manager, advisor, and marketer. Marques is also the head writer and founder of

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