Here’s the Number of Stamps Needed to Send a Letter or Package

Single stamp on the upper right corner of an envelope

The cost of mailing depends on the size, weight, and sometimes the destination of what you’re mailing, which can make it challenging to use stamps correctly.

However, stamps are convenient; they allow you to prepare your mail for shipping and drop it off without waiting in line to pay for postage.

Below, we have your guide to using stamps — how many you’ll need to send letters and packages, what kind of stamps and envelopes to use, and more.

How Many Stamps Do You Need to Send a Letter, Package, Etc?

How many stamps you need will vary depending on several factors.

The weight of your item is most important to consider — this will determine whether you can send it using stamps or need to visit the post office counter to pay for postage.

We explain how many stamps you need for various types of letters and packages below.


Letters in standard business envelopes typically need one standard First-Class or Forever stamp. Most letters weigh one ounce or less, and one stamp covers up to one ounce (as previously reported).

Heavier Letters

If your letter weighs over one ounce, you’ll need one to three Additional Ounce stamps (worth $0.20 each).

If you’d prefer to use one stamp than a combination of standard and Additional Ounce stamps, also available are two-ounce ($0.75) and three-ounce stamps ($0.95), which cover standard rectangular envelopes with heavier contents.[1]

Non-Rectangular or Oversized Letters

Things like cards and wedding invitations, which don’t fit the standard rectangular envelope shape or size and may be bulky or uneven, are considered “non-machineable.” These require $0.75 in postage for one ounce.[2]

Depending on the weight of your letter, you can usually use one two-ounce or three-ounce stamp.

International Letters

In total, you’ll pay between $0.55 and $1 in postage and can mail letters up to three and a half ounces in weight as stamped First-Class Mail.

Note that international mail is priced separately; one global stamp for a letter one ounce or less costs $1.20 at the time of writing.[2]


Postcards don’t require a standard postage stamp because they weigh less than a letter. Instead, you can purchase a postcard stamp for $0.35, and you’ll only need one for each postcard.[2]


You can use stamps for large envelopes and small parcels, but your package must meet the First-Class Mail weight restrictions set by the USPS — no larger than 15.99 ounces.

Depending on the weight of your package, you may want to use several two-ounce or three-ounce stamps rather than using more one-ounce stamps.

Because knowing the weight of your mail is crucial to affixing the correct postage, it may be best to go to the post office when sending packages to avoid incorrect estimations.

If you underpay, the post office will either return the mail to you, or the recipient will need to pay the remaining amount.[3]

Estimating the Total Cost of Postage

If you’re planning to send a lot of mail of varying sizes, an inexpensive digital scale can facilitate the process of determining postage fees.

If sending letters, consider the weight of paper: about 0.16 ounces per sheet and per business-sized envelope.

Once you know the weight, plug the letter or package’s dimensions into the USPS postage calculator and get the exact postage amount needed.

If you don’t already have stamps, you can visit the USPS online store to buy them.

You can also estimate your total postage by determining the category of mail. In order to pick the right category of mail (and determine the correct first-ounce rate), we detail the overall limits for each category below.


Letters include regular envelopes — the most popular size is #10 (measuring 4 1/8″ by 9 1/2″), though varied styles are available, including some with security features or plastic windows.

  • Size limit: 3.5 ounces; after that, it’s considered a large envelope.
  • First-ounce rate: $0.55
  • Additional ounces: $0.15 each

Large Envelopes/Flats

Large envelopes or flats are bigger and thicker than regular envelopes — best for things that you don’t want to bend during mailing.

  • Size limit: To qualify as a large envelope or flat, it must have one dimension that is greater than 6 1/8″ high OR 11 1/2″ long OR 1/4″ thick. It must also be no more than 12″ high by 15″ long by 3/4″ thick. The weight limit is 13 oz; after that, it’s considered a package or parcel.
  • First-ounce rate: $1
  • Additional ounces: $0.20

First-Class Parcels/Packages

Parcels and packages can include boxes or envelopes that exceed the weight limit or maximum dimensions for large envelopes and flats.

  • Size limit: 15.99 ounces; after that, you can use Priority Mail or Priority Mail Express, which offer flat rates for different box and envelope sizes.
  • First-ounce rate: $5.04 to $5.70 depending on your zone for First-Class Package Service
  • Additional ounces: None; the prices range from $5.04 to $5.70 for all First-Class packages of 13.01 to 15.99 ounces

Padded Envelopes

Padded envelopes may fit into either the large envelope category or the parcel/package category.

Many padded envelopes fit the size requirements for large envelopes. However, because they’re designed for sending contents other than papers, your envelope may be too bulky to fit the large envelope classification.

If this is the case, you will pay the parcel/package rate based on weight and zone.


  • Natalie

    I want to ship First Class Mail to multiple places around the US. The package is 11oz. How many stamps will it take to do this?

    Online is says $3.93, but when I went to the post office, they said $4.11

    Which one is correct?

    • First Quarter Finance logo
      First Quarter Finance | Laura Bachmann

      Hi Natalie,

      I think someone’s scale is a bit off. I tried the calculator on the USPS website and got $3.93 for an 11-ounce package. I got $4.11 for a 12-ounce package. So, I would guess that if you weighed at home and then they weighed it at the post office, one of you has a scale that is one ounce off.

      Stamps are currently $0.49, so it’ll take eight stamps if the package is $3.93 and nine stamps if the package is $4.11.

  • Diana Bartolomei

    How many stamps for a birthday card to Spain? Do I have to purchase them at pist office, or can I use the correct amount in the regular forever stamps?

    • First Quarter Finance logo
      First Quarter Finance | Rebecca Turley

      Hi Diana,

      A USPS First-Class Mail® International Large Envelope (Max. length 15″, height 12″ or thickness 3/4″) to Spain will cost you about $12.60. Yes, you can choose to use the forever stamps to cover this cost, although it may be easier to head to the post office and pay them directly to mail it for you.

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