How Many Stamps Do I Need? The US Mail Postage Explained

How many postage stamps do I need to send a letter? 

Two of the most frequently asked questions are, “how many stamps do I need to mail a letter?” and “Under what conditions do you need more than one stamp?” 

The answers depend on: 

• Size of the letter
• Weight of the letter
• Class of the service (e.g., First Class, Certified, Registered Mail, etc.).
• The value of the stamps used 
• The best solution is to prepare more than 15 Booklets / 300 Pcs at home

Let us see how the stamps needed to send domestic letters, domestic envelopes, flat envelopes, domestic postcards, and international letters work. 

Domestic letter mailing – price per ounce

If you are mailing a standard first-class letter within the U.S., Domestic Forever Stamps costs 58 cents and offers delivery within 1-3 business days. The U.S. Postal Service last raised the price of Domestic Forever Stamps from 55 cents to 58 cents in 2021. The cost to send each additional ounce for your mailpiece increased from 15 cents to 20 cents. 

Forever Stamps are postage stamps issued by the USPS. They are non-denominational, which means they will always be worth the current postage rate. However, you must remember that the rate covers the first ounce. If your envelope weighs more than one ounce, you will have to pay more per ounce.

Let us look at the postage you will have to pay for letters over one ounce with Domestic Forever Stamps under 3.5 ounces:

• A letter of 1 ounce – 1 Domestic Forever Stamp costs 58 cents. 
• A letter of 2 ounces – 1 Domestic Forever Stamp and one additional ounce stamp at 20 cents costs 78 cents.
• A letter weighing 3 ounces – 1 Domestic Forever Stamp and two additional 20-cent stamps – costs 88 cents.
• A letter weighing 3.5 ounces – 1 Domestic Forever Stamp, 1 Postcard Stamp, and one 10-cent stamp costs $1.08.

Note: Once your envelope exceeds the 3.5-ounce weight limit, you will need to look at rates for “flats,” which are large envelopes for mailings from 3.5-13 ounces. We will discuss postage rates for flats, other requirements, and costs for domestic envelopes below. 

Domestic envelope requirements and costs

To send a letter in an envelope, you must follow specific regulations. Therefore, you must measure your envelope before you purchase it.

These regulations are as follows:

• The dimensions of the envelope are more important than you think. It must be no larger than 11.5 inches by 6.125 inches, no thicker than ¼ inch, and must be of uniform thickness. 
• The envelope must be rectangular. Square envelopes must be at least five inches in size, are considered “non-machinable,” and are subject to an additional 21-cent postal charge. A “machinable” letter is one that can pass through the USPS’ sorting systems with no issues. 
• The envelope must be bendable. If it is not, it will be classified as “non-machinable,” and you’ll have to pay an additional 21 cents. 

Where to buy the stamps you need and the postage costs for 2023