How Many Stamps Do I Need? | (Complete Guide)

Mailing a letter or package might seem like a simple task, but things can get complicated if you are not sure how much postage is needed. You may end up really frustrated if the letter is returned to you for insufficient postage. Or some people just add way more stamps than needed. The USPS will not deliver mail that does not have enough postage on it, and you will not get reimbursed for any excess postage used. So, how do you determine exactly how many stamps per ounce your letter or package needs? You will need a few pieces of information like the size and weight of the letter, and we will explain all those details here. So, keep reading and you will be ready to send that mail with the proper number of stamps to ensure that it makes it to the delivery address.

How Many Stamps Do I Need To Send A Letter In The United States?

A letter sent in a standard size envelope weighing 1 ounce or less will require $0.66 of postage or one forever stamp. Each additional ounce is an extra $0.24 in postage. So, a two-ounce letter will cost you $0.90 while a three-ounce one will cost $1.14. Instead of placing two forever stamps on a two-ounce letter, you can place a single first-class stamp plus an additional ounce stamp. These stamps cost $0.24 and can be purchased at your local post office.

Note that the prices above are for standard size envelopes. If you are mailing a larger letter, then the postage rates will be higher. If an envelope exceeds 6.125 inches high, 11.5 inches wide, or 0.25 inches thick, then it is considered a large envelope. Mailing a first-class letter in a large envelope weighing 1 ounce or less will cost $1.35. Each additional ounce will cost you an extra $0.24. See the table below which shows exactly how many stamps you will need to mail your letter through USPS.

USPS First-Class Letter - Stamp & Postage Guide - 2024

How Many Stamps Do I Need To Send A Parcel In The United States?

When it comes time to mail a package, the first question that often comes to mind is, “How much postage do I need?” Calculating postage for standard letters is fairly simple while determining how many stamps you need for a parcel or package is more difficult. The shipping cost for a package depends on both the size and weight of the package as well as what type of service you are requesting, so a little bit of shipping know-how is required to calculate this on your own. Since you will likely have to drop the package off at the post office anyway, the easiest thing to do is let the mail clerk determine the amount of postage needed. This way, you can ensure that it is correct, and they can assist with answering any questions about the type of service requested.

However, if you want to print your own shipping label and get the package sent off without visiting the post office, then here is what you will need to do. First, you need to go ahead and measure and weigh the package. You will need all the dimensions of the package including the height, width, and thickness of the package. Next, determine the weight to the nearest ounce. Finally, you will need both the originating and destination ZIP codes for the package. The distance that the package must travel is also used in calculating the postage cost.

Once you have all the information you need, then head on over to the USPS postage calculator. Here, you can fill in all the required information regarding the package. In addition, you will select the type of service that you need. You might select first-class mail, priority mail, international mail, or some other service that meets your needs. Once you make your selection and have filled in all the required information, the tool will tell you the postage price. You are also given the option to go ahead and buy the postage and print the label.

You might also choose to use a flat rate envelope. These are great options if you do not want to go through the trouble of determining the weight of the envelope or package. You can simply stuff as much as possible into the box, and the US Postal Service will deliver the package for a flat rate. This is also great for Amazon or eBay sellers who want to keep their shipping expenses consistent. As long as the item fits in the flat rate box, then it ships for the same price.

USPS Ground Advantage Parcel Rate Table

(On smaller screens this table is best viewed in widescreen).

How Many Stamps Do I Need To Send A Letter Internationally?

A letter weighing 1 ounce or less, sent in a standard size envelope, will cost $1.50 for a global forever stamp. The cost of each additional ounce up to 3.5 ounces varies by country. Sending a large envelope internationally starts at $3.00 for the first ounce, and varies by country for each additional ounce, up to a max of 15.994 ounces. If your envelope is heavier than this or has an irregular shape, you’ll have to mail it at package rates.

USPS International Letter Stamp Rate Table

To use this table, you will need to know your destination country’s “Price Group”. If you don’t know it, you can find it here.

(On smaller screens this table is best viewed in widescreen).

How Many Stamps Do I Need to Send a Package Internationally?

For an international package weighing up to 8 ounces, postage starts at $15.75 and goes up to $21.70 depending on the destination country. Below is a chart showing the cost for First-Class international service, though it’s important to note that USPS offers other classes of services.

USPS International Package Stamp Rate Table

To use this table, you will need to know your destination country’s “Price Group”. If you don’t know it, you can find it here.

(On smaller screens this table is best viewed in widescreen).

The Bottom Line

Not placing enough stamps or postage on your letter or package can have dire consequences and will cause the mail to be returned to you instead of being delivered to the addressee. The United States Postal Service has clear rules on how many stamps are required for letters. A standard mail letter will cost you $0.66 cents for the first ounce plus $0.24 cents for each additional ounce. Larger letters will require additional postage and the pricing for package mailers is based on the size, weight, and destination of the package.

Frequently Asked Questions

How do I know how many stamps to use?

People often ask, “How many stamps do I need per oz to mail a letter?” If you are mailing a one-ounce letter in a standard size envelope to a destination in the United States, then you will only need one domestic forever stamp. For each extra ounce, you will need to add another twenty-cent stamp. So, for example, a 2 oz letter would cost you $0.90 to send it via first-class mail. For larger envelopes or packages, you will need the size and weight of the package. 

How many stamps do I need for a 9×12 manila envelope?

This type of envelope would qualify as a large letter, so you would need to place two stamps on it. For mailing larger letters up to 1 ounce, the postage required is $1.35. Each ounce above that limit will cost you an extra $0.24 up to 3.5oz. Once the letter is above 3.5 ounces, then it is considered a flat package and no longer a letter.

How many stamps do I need for 4 oz letter?

There is no single answer to the question, It depends on the size of the envelope or package. A first-class letter can weigh no more than 3.5 ounces. Once your letter goes above that weight, it is then considered a flat package and the letter postage rates no longer apply.

How many stamps are there in a pack?

A typical pack of stamps contains 20 stamps. You may also purchase a roll of stamps which includes 100 stamps. If you need to purchase fewer than 20 stamps, they can be purchased individually from your local post office. However, most retailers require the entire pack to be purchased at once.

How much does a stamp cost?

A standard domestic first-class stamp will cost you $0.66. If you need to send a letter outside the country, the international forever stamp costs $1.50. Both domestic and international forever stamps never expire, and you can use them to send letters at any time in the future even if the price of postage increases.

Where can I buy stamps?

You can buy stamps at many locations. This includes your local post office, USPS.com, and many retailers like grocery stores and pharmacies. Many well-known retailers like Wal-Mart allow you to easily buy stamps right at the checkout.

How many stamps do I need for a postcard?

The postage required to deliver a postcard is generally less than the postage required for a letter, but it depends on the size of the postcard. A single standard postcard stamp only costs $0.51. You only need one postcard stamp to mail a postcard. This will save you twenty cents over the price of mailing a standard letter.