When mailing letters or packages, one of the most common questions is “How many stamps do I need?” The answer depends on the weight and size of the mail piece, as well as the class of mail service used. The United States Postal Service (USPS) has specific postage requirements based on weight and service type. This article provides a detailed breakdown of the number of stamps needed for different weights and mail classes.
First-Class Mail
For standard enveloped letters weighing 1 oz or less, you need 1 first-class stamp. The current price of a first-class stamp is $0.60. So if your letter weighs 1 oz or less, you need 1 $0.60 stamp to mail it first-class.
For heavier first-class mail, you need additional postage based on weight increments called ounces. Each additional ounce over 1 oz requires $0.25 extra postage. Here are the first-class stamps needed per weight increment:
| Weight | Stamps Needed |
| 0 – 1 oz | 1 Stamp |
| 1.1 – 2 oz | 2 Stamps |
| 2.1 – 3 oz | 3 Stamps |
| 3.1 – 4 oz | 4 Stamps |
| 4.1 – 5 oz | 5 Stamps |
| 5.1 – 6 oz | 6 Stamps |
| 6.1 – 7 oz | 7 Stamps |
| 7.1 – 8 oz | 8 Stamps |
| 8.1 – 9 oz | 9 Stamps |
| 9.1 – 10 oz | 10 Stamps |
| 10.1 – 11 oz | 11 Stamps |
| 11.1 – 12 oz | 12 Stamps |
So in summary, for first-class mail:
- 1 stamp for 0-1 oz
- Add 1 extra stamp for each additional ounce over 1 oz
Priority Mail
For Priority Mail service, the postage is based on both weight and zone. Zone refers to how far the package is traveling. There are 9 postal zones in the contiguous United States based on distance from the point of origin. The farther the package is traveling, the higher the zone number and postage cost. Alaska, Hawaii, and US territories have different zone maps.
The USPS provides a Priority Mail postage calculator on their website to determine the exact postage cost by weight and destination zone. But as a general rule of thumb, most Priority Mail under 1 lb can be sent with 1 or 2 stamps, and packages between 1-4 lbs may need 3-5 stamps depending on zone.
Here are the approximate stamps needed for different Priority Mail weights to Zone 1-4 (closest zones):
| Weight | Zone 1,2 Stamps | Zone 3 Stamps | Zone 4 Stamps |
| 0 – 1 lb | 1 Stamp | 2 Stamps | 3 Stamps |
| 1 – 2 lbs | 2 Stamps | 3 Stamps | 4 Stamps |
| 2 – 3 lbs | 3 Stamps | 4 Stamps | 5 Stamps |
| 3 – 4 lbs | 4 Stamps | 5 Stamps | 6 Stamps |
Keep in mind Priority Mail postage is charged by weight AND zone. The farther the package is traveling, the more it will cost to mail. Use the USPS postage calculator to determine exact rates.
USPS Retail Ground
USPS Retail Ground is the lowest cost option for packages that don’t need to arrive quickly. It can take 2-8 days for delivery. The postage is calculated by weight and zone.
Here are approximate stamps needed for Retail Ground to zones 1-4:
| Weight | Zone 1 Stamps | Zone 2 Stamps | Zone 3 Stamps | Zone 4 Stamps |
| 0 – 1 lb | 3 Stamps | 4 Stamps | 5 Stamps | 6 Stamps |
| 1 – 2 lbs | 4 Stamps | 5 Stamps | 6 Stamps | 7 Stamps |
| 2 – 3 lbs | 5 Stamps | 6 Stamps | 7 Stamps | 8 Stamps |
| 3 – 4 lbs | 6 Stamps | 7 Stamps | 8 Stamps | 9 Stamps |
| 4 – 5 lbs | 7 Stamps | 8 Stamps | 9 Stamps | 10 Stamps |
| 5 – 6 lbs | 8 Stamps | 9 Stamps | 10 Stamps | 11 Stamps |
| 6 – 7 lbs | 9 Stamps | 10 Stamps | 11 Stamps | 12 Stamps |
Always check the USPS website for exact Retail Ground rates. But in general, expect to use 3-10 stamps depending on weight and destination zone.
Media Mail
Media Mail is a special USPS service for mailing books, CDs, DVDs, and other media items. The postage cost is calculated by weight only, regardless of zone. Here are the approximate stamps needed for different Media Mail weights:
| Weight | Stamps Needed |
| 0 – 1 lb | 1 Stamp |
| 1 – 2 lbs | 2 Stamps |
| 2 – 3 lbs | 3 Stamps |
| 3 – 4 lbs | 4 Stamps |
| 4 – 5 lbs | 5 Stamps |
| 5 – 6 lbs | 6 Stamps |
| 6 – 7 lbs | 7 Stamps |
| 7 – 8 lbs | 8 Stamps |
| 8 – 9 lbs | 9 Stamps |
| 9 – 10 lbs | 10 Stamps |
| 10 – 11 lbs | 11 Stamps |
| 11 – 12 lbs | 12 Stamps |
In summary, Media Mail postage is calculated solely by weight, so make sure to weigh your package and add roughly 1 stamp per pound.
Large Envelopes (Flats)
If you are mailing a large envelope, flat, or padded envelope that exceeds the size limits for standard first-class mail, it is considered a “flat” by USPS standards. Flats exceeding 1 oz in weight require additional postage based on weight increments.
Here are the stamps needed for large envelopes/flats exceeding 1 oz:
| Weight | Stamps Needed |
| 1 – 2 oz | 1 Stamp |
| 2 – 3 oz | 2 Stamps |
| 3 – 4 oz | 3 Stamps |
| 4 – 5 oz | 4 Stamps |
| 5 – 6 oz | 5 Stamps |
| 6 – 7 oz | 6 Stamps |
| 7 – 8 oz | 7 Stamps |
| 8 – 9 oz | 8 Stamps |
| 9 – 10 oz | 9 Stamps |
| 10 – 11 oz | 10 Stamps |
| 11 – 12 oz | 11 Stamps |
So for large envelopes over 1 oz in weight, add roughly 1 additional stamp for each extra ounce.
Small Packages
For small lightweight packages like a shirt box or packaged gift under 1 lb, you can mail with First Class Package Service. This is generally the most affordable option. Here are the approximate stamps needed:
| Weight | Stamps Needed |
| 0 – 4 oz | 1 Stamp |
| 4 – 8 oz | 2 Stamps |
| 8 – 12 oz | 3 Stamps |
| 12 – 16 oz | 4 Stamps |
So for small packages under 1 lb, expect to use 1-4 first class package stamps depending on exact weight.
Large Packages
For heavier packages weighing over 1 lb, your best options are Priority Mail and Retail Ground as described earlier. Use the USPS postage calculator online to determine exact rates based on weight, dimensions, and destination zone.
As a general guideline:
- 1-2 lb packages may need 2-5 stamps depending on zone
- 2-4 lb packages may need 4-10 stamps depending on zone
- 4-8 lb packages may need 10-20 stamps depending on zone
But always use the USPS postage calculator to determine exact postage for heavy packages based on specifics.
International Mail
Mailing letters or packages internationally will require extra postage compared to domestic mail. Use these general guidelines for international postage from the US:
- Postcard: $1.40
- 1 oz letter: $1.40
- 2 oz letter: $1.60
- 1 lb package: starts at $40+ depending on destination
Since international postage costs vary greatly depending on exact weight and destination country, your best bet is to bring the item to the post office and have them weigh it and determine exact postage.
Additional Postage Options
In addition to traditional stamps, you can also pay postage online and print labels if you have a scale to weigh your package accurately. Paying online gives you access to USPS commercial rates which are discounted compared to retail postage rates. You can also order pickup so you don’t need to drop off at the post office.
Some online postage vendors include:
- Stamps.com
- Pirateship.com
- Paypal Shipping
- Etsy Shipping Labels
- Shippo
- ShipStation
This allows you to pay postage and print official USPS labels at home with discounted rates. Just make sure you have an accurate scale to weigh packages.
Conclusion
Determining postage can be tricky, but the general rule of thumb is the heavier the item, the more stamps needed. Use 1 stamp for standard 1 oz letters, and add stamps in 1 oz increments for heavier first-class mail. Priority Mail and Retail Ground packages will need roughly 1 stamp per pound, but use the USPS postage calculator for exact rates based on weight, zone and package dimensions.
The USPS offers many different shipping options at various rates depending on size, weight, speed and distance. Make sure to weigh items accurately and confirm postage rates on usps.com for the service you want to use. This will ensure you have proper postage for mailing letters, flats, and packages with ease.
