How Many Stamps Do I Need to Send a Letter?

When it comes to mailing letters, you may wonder how many stamps you need. The good news is that the U.S. Postal Service has made it easy to figure out! In this guide, you will find out how many stamps are needed based on their weight, size, and destination of the letter. So whether you’re sending a letter across the country or just across town, we have all the information you need to deliver your mail on time!

How many postcard stamps to mail a letter within the U.S.?

USPS will deliver a one-ounce letter anywhere in the United States within 1 – 3 days for only 0,60 $.  You will be charged $0.24 for each additional ounce (max. 3.5 ounces).

Weight Postage rates
1 ounce $ 0.60
2 ounce $ 0.84
3 ounce $ 1.08
3.5 ounces $ 1.32
Single peace flat* $ 1.20
Each additional ounce for flats** $ 0.24
Metered mail 1-ounce $ 0.53
One-ounce letter international (Global Forever®) $ 1.40
Postcards (standard-sized, rectangular) $ 0.44
Certified mail $ 4.00
Forever stamp $ 0.60
Square, oversized, or unusual envelopes From $ 0.99

*Envelopes that are longer than 11-1/2 inches, or wider than 6-1/8 inches, or thicker than a ¼-inch.
**Check detailed flats price here and here.

Requirements for envelopes:

  • at least 5 inches by 3.5 inches, not exceeding 11.5 inches by 6.125 inches.
  • Rectangular, bendable, and uniform thickness.
  • If it’s classified as “non-machinable”, you will have to pay a processing fee of $ 0.21.
  • It must be bendable. If not, you might have to pay an extra 21 cents since it will be considered “non-machinable”.

Forever stamp price

The new Forever stamp price is $ 0.60 (from July 10), and it covers the First-Class Mail one-ounce letter delivery in the United States.

Do stamps expire? Once purchased, Forever stamps can be used indefinitely, no matter how many times the postage price for First-Class one-ounce letter changes in the future.

Want to save some pennies in the future? Buy a pack of Forever stamps in your local post office before the subsequent price increase. Another option would be to check your stuff for some older Forever stamps.

How many stamps for a postcard?

Sending postcards is cheaper than sending one-ounce letters. When sending a domestic postcard, you will need to buy one Postcard Stamp for $ 0.44.

When feeling generous or lazy, you can use one Forever stamp ($ 0.60) for your postcard. Yes, you will pay extra, but that will be only $ 0.16 more than needed.

How Many Stamps Do I Need For A 9×12 Envelope?

For 9-inch envelopes, you must buy two domestic Forever stamps for the first ounce. If the letter is heavier, be ready to add more stamps.

Don’t want to buy Forever stamps? You can use regular stamps that match 9×12 envelope postage costs.

How to weigh the envelope?

A kitchen food scale is the most accessible and cheapest solution to weigh your envelopes. You can find them in Bestbuy, Walmart, Amazon, or any other at least medium-size supermarket.

Place the envelope on the scale and weigh it.

Where to put a stamp on a letter?

The stamp should be placed on the envelope’s top right corner near the recipient’s mailing address.

If you have to use more than one stamp, put them all in one row. If not possible to squeeze all in one row, it is ok to put on the 2nd or 3rd line.

Can you put stamps on the left side of the letter? No! It can cause difficulties for USPS machine reading equipment, and the letter might be returned. However, it will be delivered to the recipient more often than not. Thank you, USPS!

How long does it take for letters to be delivered?

According to the USPS statements, First Class Mail (letters, postcards,, and large envelopes) is delivered within 1 – 3 days. The average time for domestic mail delivery in the U.S. is 2.5 days.