How Many Stamps Per Pound (USPS)?
Going to the post office and realizing you don’t know how many stamps to buy can be tricky. How should you calculate how much postage is needed for the items you send out? Are you supposed to overbuy, or will one stamp do it?

For a long time, the US Postal service has been used as a reliable way to send both small and large packages worldwide. Shipping fees tend to increase over time – especially if your business depends on efficient logistics.
So how can you effectively determine what kind of postage you need for letters, envelopes, and packages? To help make sure that your items arrive safe and sound, here’s an overview of what’s generally required from the USPS when mailing within the United States.
How Many Stamps Per Pound? (USPS)
1. One Ounce
The general rule for sending a one-ounce letter or postcard is to put one First-Class stamp on the envelope. One First-Class stamp currently costs $0.55, so you’ll need to purchase this amount of stamps per pound.
2. Two Ounces
If you need to mail an item that weighs two ounces, you’ll need to use two First-Class stamps. This means that sending a standard postcard or flat item of two ounces or less would cost $1.10 in postage stamps per pound.
3. Three Ounces
For items between three and three and a half ounces, three First-Class stamps would be needed per pound ($1.65). You can also opt to pay with one ‘Forever’ stamp, which is always worth $0.55 regardless of future changes in stamp prices ($0.55).
4. Metered Mail
This alternative method allows you to use postage meters that weigh the mailpiece and print the correct amount directly onto your envelope ($0.50). This is especially useful for businesses and organizations with higher volume mailings due to the savings per pound compared to using stamps ($0.05).
5. Six Ounces
Sending more oversized items, such as letters over six ounces, requires additional postage beyond what is covered by single Forever Stamps or metering machines ($3). The cost of sending these heavier items is that each additional ounce up from six starts at a rate of $0.15 per ounce, meaning you will need an additional 15 cents worth of First Class Postage stamps against each ounce above 6 ounces (ex: 7 adds $ 0 .15, 8 adds $ 0 .30 )($3 + 0 .30 $3 .30).
6. Other Postal Services
USPS also offers other domestic classes such as Priority Express Mail, Priority Mail Flat Rate Envelopes & Boxes, Media Mail, and Library Mail, available at different price points depending on the weight of an item($7 – 487 ). All services are accessible online through USPS but keep in mind rates may vary since they are based on distance and type of shipping service used($7 – 487 ).
How many postage stamps do I need to send a letter?
When sending a letter, the number of stamps needed depends on the size, weight, class of service, and value of the stamps used. Domestic letters require one stamp; domestic envelopes require two stamps; and domestic postcards require one stamp. International letters require additional postage. To determine the exact amount of postage needed for a specific letter or envelope, visit the USPS website for more information.

Calculating postage for parcels is more complicated than for domestic letters. Factors to consider include the parcel’s weight, size, and distance. There are two ways to calculate how many stamps are needed: an online calculator or visiting your local post office. Online calculators provide an estimate based on your information, while post offices can provide an exact amount based on their current rates. It is important to remember that when sending parcels internationally, additional fees may apply depending on the destination country’s regulations.
Domestic letter mailing – price per ounce
Domestic letter mailing is a convenient and cost-effective way to send mail within the United States. The weight of the mailpiece determines the price per ounce for domestic letters. For letters up to one ounce, the cost is 58 cents, with delivery within 1-3 business days. Each additional ounce costs 20 cents, so a three-ounce letter requires 88 cents in postage. If your letter weighs more than one ounce but less than 3.5 ounces, you will need to purchase a Domestic Forever Stamp plus additional stamps for each additional ounce. For example, a 3.5-ounce letter requires 1 Domestic Forever Stamp, 1 Postcard Stamp, and one 10-cent stamp, costing $1.08 in total postage. Envelopes exceeding the 3.5-ounce weight limit require postage rates for “flats” (large envelopes from 3.5-13 ounces). USPS offers a variety of domestic and international mailing and shipping options with prices listed on their Priceenvelope requirements and costs
Envelopes used for domestic mail must adhere to a certain size and weight requirements in order to be accepted by the United States Postal Service (USPS). The envelope must be no larger than 11.5 inches by 6.125 inches, no thicker than ¼ inch, and of uniform thickness. Square envelopes must be at least five inches in size and are subject to an additional 21-cent postal charge. Additionally, the envelope must be bendable, or else it will incur an additional 21-cent charge for being classified as “non-machinable.”
The cost of postage depends on the weight of the mailpiece. Domestic Forever Stamps cost 58 cents and offer delivery within 1-3 business days. The total postage cost is 58 cents plus 20 cents per additional ounce for letters over one ounce. For example, a letter weighing 3 ounces requires 1 Domestic Forever Stamp and two additional 20-cent stamps, costing 88 cents; a letter weighing 3.5 requires and costs for flats.
Flats are a great way to send mail quickly and cost-effectively. However, certain requirements must be met for them to be accepted by the post office. Flats must be between 6.125 inches by 11.5 inches and 12 inches by 15 inches and no thicker than 0.75 inches. A bubble packet is not allowed as it makes it too thick. The cost of postage for a 1 oz flat can vary depending on the combination of stamps used. Envelopes must also meet certain requirements, such as being no larger than 11.5 inches by 6.125 inches, no thicker than ¼ inch, and of uniform thickness. Square envelopes must be at least five inches in size and are subject to an additional 21-cent postal charge.
Domestic postcard shipping
Postcards are a great way to keep in touch with friends and family, and they can be sent domestically for a relatively low cost. In the United States, postcards mailed within the country require a 40 cent postcard stamp, which is cheaper than a Domestic Forever Stamp. Postcards must also meet certain size requirements; they must be at least 3.5 inches high and 5 inches long but no larger than 4.25 inches high and 6 inches long. Additionally, postcards must be rectangular and between 0.007-0.016 inches thick in order to qualify for domestic shipping rates.
For international shipping, Global Forever Stamps cost $1.30 to mail letters from the U.S. to the U.K., while Domestic Forever Stamps must total at least $1.30 for international shipping as well. Additional postage is required for letters weighing more than one ounce, so it’s important to check the weight of your postcard before sending it off shipping letter postage.

International shipping of letters can be tricky, but with the right knowledge and preparation, it can be done quickly and easily. The U.S. Postal Service offers Global Forever Stamps for $1.30 that can be used to mail letters from the U.S. to the U.K., while domestic Forever Stamps must total at least $1.30 for international shipping. If the letter weighs more than one ounce, additional postage is required; First Class Mail International Letters (1 oz.) cost $1.30, while Priority Mail International (1 lb.) to Canada costs $37.47 and Priority Mail Express International Flat Rate Envelopes to Canada cost $44.95. Knowing these rates ahead of time will help ensure that your letter arrives safely and on time without any extra charges or delays due to insufficient postage fees.