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How many stamps do I need? And where to buy?

Joanna Heep

July 26, 2021

How many stamps do I need? And where to buy?

If you’re mailing anything besides an ordinary letter, how many stamps do you put on an envelope?

The number of stamps you put on letters or packages depends on the envelope size and its weight. If you don’t have the time to go to a postal store before calculating how many stamps you need, here’s a guide that will help you. 

How many stamps do I need?

There’s no easy answer to how many stamps your mail item needs, because it’s dependent on many different things such as weight, size, and receiver’s location. In most cases, a single postage stamp will suffice to mail a letter. That changes for irregularly shaped envelopes, heavy envelopes, or oversized envelopes.

When figuring out how many stamps you need to mail your letter or postcard, your postage costs will depend on the shape and size of your mail. If your envelope isn’t flat, it won’t fit in automated processing equipment and you will be charged more.

  • Standard letters. If your letter is a standard sized envelope and weights 3.5 ounces or less, you will need one stamp

  • Large envelopes. This includes 9x12, legal, and manila envelopes, Two stamps are needed for the first ounce, and postage will be an additional $0.20 cents after. 

  • International mail. For mail going outside of the United States, you can use Forever Stamps or a Global Forever Stamp ,which currently costs $1.20 each. If your letter is one ounce or below, you will need one Global Forever stamp or three Forever Stamps. 

  • Packages. The number of required stamps depends on the weight and size of the package. Usually the first four ounces need minimum $3.80 in postage, with more postage as weight increases. Shipping costs vary depending on weight, or you can purchase a priority mail box, which ships at a flat rate if it fits inside the USPS produced boxes. 


It’s not just the weight that matters. All postcards and envelopes must be rectangular. If you’re sending square-shaped stationary or a specialty envelope, you should put an extra stamp on it.  

Still not sure? USPS has a postage price calculator. 

How many Forever Stamps do I need?

Forever Stamps, created in 2007, are postage not tied to a fixed price, so they remain valid to mail letters even when rates increase.  Basically, they are stamps with grandfathered pricing. 

If you have Forever Stamps, you calculate them as worth the current postage rate, even if you bought them before the rate increased. 

USPS changing the rates of its postage stamps

In it’s 10-year plan reveil, the United States Postal Service (USPS) announced the upcoming changes to the government service. One of the changes being implemented is its second postage stamp rate increase of the year on August 29th, 2021. The first increase came at the beginning of the year in January.


Right now, stamps cost $0.55. Beginning August 29th, 2021, that will increase: 

  • First Class Mail letters will increase by 3 cents (from $0.55 to $0.58) for 1 ounce. Each additional ounce will be $0.20. 

  • First Class Mail postage purchased online on Stamps.com will increase by 2 cents (from $0.51 to $0.53).

Now’s the time to stock up on your Forever Stamps so you save money in the long run!

Where to buy stamps online

The U.S. Postal Service has an online store of its stamp collection where you can purchase as many stamps as you’d like. Or there are other online retailers such as Stamps.com that sell stamps and allow you to buy and print postage from your home. 

If you don’t want to purchase online, you can buy stamps at your local post office or by phone at 1-800-STAMP-24. 

Additionally, you can often purchase a book of stamps at gas stations, grocery stores, and pharmacies. 

The modern way of managing your mail

Heard of a virtual mailbox? It’s like your home mailbox, but does the work for you while giving you an added layer of privacy and security.

An Earth Class Mail virtual mailbox allows you to view mail sent to a virtual mailing address of your choice as it comes to our secure processing facility. You can set up your account so that we automatically scan your mail items and you only have to view and manage the mail scanned in your account. 

With your account, you can sort, save, or share those PDFs, so you can easily organize all your incoming mail. Virtual mailboxes are especially helpful if postal workers have a difficult time delivering mail to your home address.

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