Figuring out how much postage is required to mail a letter or package to another state can seem complicated. The number of stamps needed depends on the weight, shape, and size of the mail piece as well as the class of mail service used. This guide will provide a breakdown of the most common types of mail classes and services to help you determine exactly how many stamps you’ll need to affix to your mail.
What Mail Classes Are Available for Sending Mail to Another State?
The United States Postal Service (USPS) offers several different mail classes that can be used to ship letters, flats (large envelopes), and packages within the United States and to U.S. territories. The main classes of mail used for interstate mail include:
- First-Class Mail
- USPS Retail Ground
- Priority Mail
- Priority Mail Express
- Parcel Select Ground
- Media Mail
- Library Mail
Each mail class has different service standards, prices, and included features. The type you choose will depend on your specific mailing needs.
First-Class Mail is used for letters, postcards, bills, payments, and other enveloped mailpieces. It provides delivery in 1-3 business days within the continental U.S. First-Class Mail is the cheapest way to send 1-ounce letters and postcards. Additional postage is required for heavier pieces.
USPS Retail Ground
Previously known as Standard Post, Retail Ground offers economical ground shipping for packages. Delivery time is 2-8 business days. Retail Ground is cheaper than Priority Mail for heavy packages going to zones 3-8.
Priority Mail provides 1-3 day delivery of mailpieces weighing up to 70 pounds. Flat rate priority mail options are available for envelopes and boxes. Priority Mail rates are based on weight and distance traveled.
Priority Mail Express
Priority Mail Express offers overnight delivery to most addresses in the U.S. Rates are based on weight and zone. This is the fastest domestic shipping option offered by USPS.
Parcel Select Ground
Parcel Select Ground provides ground transportation and delivery in 2-8 business days. It offers commercial base pricing for packages sent to zones 1-8. Discounts are available for large volume mailings.
Media Mail rates are offered for the shipment of books, CDs, DVDs, and other educational media. Delivery takes 2-8 business days. Media Mail is cheaper than Parcel Select Ground but does not include tracking or insurance.
Library Mail works similarly to Media Mail but is only for use by libraries and other eligible organizations to send books, audio recordings, and other media. It offers the lowest postal rates without a discount.
How is Postage Price Calculated?
The amount of postage required for a mailpiece is based on a combination of factors:
- Weight – Heavier packages require more postage. First-Class mail is priced per ounce. Priority Mail and Retail Ground prices are based on weight increments.
- Size – Oversized or irregularly shaped mail may incur surcharges.
- Distance – The farther a package is traveling, the higher the rate. USPS divides the U.S. into 9 zones for rating purposes.
- Mail Class – Each class has a different price structure. First-Class is the most expensive for regular letters under 13 ounces. Retail Ground is cheaper for heavy packages.
- Added Services – Options like certified mail, tracking, insurance, and signature confirmation add to the final postage cost.
The weight and destination of the mailpiece are the two biggest factors that determine how much postage you’ll need. USPS provides price calculators on their website to determine exact postage costs.
How Much Does a Forever Stamp Cover?
A forever stamp can be used to mail a standard 1 ounce letter regardless of any future price increases. The current value of a forever stamp is:
- Letters – 1 ounce
- Large Envelopes (flats) – 1 ounce
- Small Packages (applies to Retail Ground only) – 1 ounce
If you are mailing something heavier than 1 ounce, a forever stamp will not cover the full cost. You’ll need to use additional postage to make up the difference. For Priority Mail and other classes, a forever stamp does not hold a set value – the full rate for that class must be paid.
How Many Stamps for a Standard Letter?
A standard letter that weighs 1 ounce or less and is being sent via First-Class Mail within the United States requires just 1 forever stamp:
- Standard letter (up to 1oz) – 1 forever stamp
- Postcard – 1 forever stamp
- Square, oversized, or oddly shaped envelope (up to 1oz) – 1 forever stamp
If your letter weighs more than 1 ounce, you’ll need to add 1 forever stamp for each additional ounce. For example:
- 1.1 oz letter – 2 forever stamps
- 2 oz letter – 3 forever stamps
- 3 oz letter – 4 forever stamps
Be sure to weigh your letter to determine exactly how many stamps are required. Oversized or irregularly shaped envelopes may cost more.
How Many Stamps for Large Envelopes (Flats)?
If you are using First-Class Mail to send a large envelope (flat), a forever stamp covers up to 1 ounce. After that, you’ll need to add postage for each additional ounce:
- 1 oz large envelope – 1 forever stamp
- 2 oz large envelope – 2 forever stamps
- 3 oz large envelope – 3 forever stamps
Large envelopes include the following:
- Envelopes exceeding 6-1/8″ high x 11-1/2″ long x 1/4″ thick
- Envelopes that are square, triangular, or are not uniformly thick
- Rigid envelopes made of cardboard, plastic, etc.
If your large envelope weighs more than 13 ounces, you cannot use First-Class Mail. You would need to send it using Priority Mail or Parcel Select Ground and pay the corresponding rate.
How Many Stamps for a Postcard?
A standard postcard only requires a single forever stamp:
- Standard postcard – 1 forever stamp
Postcards are defined as:
- Rectangular cards from 5″ x 3.5″ minimum to 6″ x 4.25″ maximum
- .007 thick minimum to .016 thick maximum
Oversized postcards that exceed these dimensions would still require 1 stamp since they weigh less than 1 ounce. However, irregular shaped postcards like ones that are triangular or circular may cost more.
How Many Stamps for Packages and Priority Mail?
If you are using USPS Retail Ground, Priority Mail, Priority Mail Express, or Parcel Select Ground to ship a package, stamps don’t determine the postage cost. These classes use different rate structures based on weight brackets and distance zones. To figure out how much postage you need:
- Weigh your package on a scale
- Measure its dimensions and enter them into the USPS price calculator along with origin, destination, and mail class
- Pay the calculated price (forever stamps cannot be used)
For Priority Mail Flat Rate options like the Priority Mail Flat Rate Envelope, the price is the same regardless of weight or distance, so no calculation is necessary. Just pay the Flat Rate price.
Examples of USPS Package Rate Pricing
|Zone 5 Rate
|Zone 8 Rate
|2 lb Retail Ground
|3 lb Priority Mail
|1 lb Priority Mail Express
As shown, sending packages across longer distances in higher zones incurs a higher rate. Priority Mail is faster than Retail Ground but costs more. Priority Mail Express is the quickest option and most expensive. Calculate your exact rate online using the USPS price calculator.
How Many Stamps for Certified Mail?
If you are sending certified mail to prove that an article was delivered, you will need:
- Postage for the weight class of your mailpiece (1 stamp for 1 oz letter, 2 stamps for 2 oz letter, etc)
- $3.75 fee for certified mail service
The $3.75 certified fee can be paid for with a combination of forever stamps and other denominations like $1 or $2 stamps to equal the exact amount. Or you can pay for it entirely with a $3.75 certified mail stamp.
How Many Stamps for Registered Mail with Insurance?
To send a letter or package using registered mail service with insurance coverage, you’ll need to pay:
- Postage for the weight of your mail (1+ forever stamps for letters, online price for packages)
- $14.75 registered mail fee
- Insurance fee if electing to purchase coverage
Registered mail with insurance would require additional stamps or payment to cover the fees. For example, a 2 ounce registered letter with $100 of insurance coverage would need:
- 2 forever stamps for the weight
- $14.75 for registered mail
- $2.15 for $100 of insurance coverage
Visit your local post office or use the USPS Postage Price Calculator online to determine the exact postage rate.
Using Extra Stamps for Future Postage
If you aren’t sure exactly how much postage you’ll need, you can always affix extra stamps to envelopes and mailpieces. If you end up using more postage than required, there are two options:
- Reuse Leftover Postage – Carefully peel off stamps that aren’t cancelled by the post office and save them to use again later.
- Forever Stamp Value – Any extra forever stamps you use will always be valid to cover 1 ounce letters, even if rates increase in the future.
It’s better to use a few extra stamps than to underpay postage. Mail with insufficient or unpaid postage may be returned, delayed, or the recipient may have to pay charges upon delivery.
Checking USPS Postage Price Calculators
To find the exact postage needed for any mail class, use the handy price calculators at USPS.com. Resources include:
- Postage Price Calculator – Get prices for different mail classes based on your exact weight, origin ZIP code, destination ZIP code, date of mailing, and added services.
- Postage Rates Lookup – Quickly look up prices for common mailpieces like letters, flats, postcards, packages, and Priority Mail options.
- Zip Code Lookup – Find the zone for any ZIP code pair to determine your price zone.
These tools make it easy to calculate the precise amount of postage required. Punch in the details and you’ll get the total rates displayed including any fees.
Using a Postage Scale
Investing in a small digital postage scale can make determining mail rates much simpler. You can weigh your mail pieces and packages at home to get accurate weights for the price calculators. Scales are available at office supply stores, Amazon, and other major retailers. Look for one that can handle typical letter and package weights.
With a scale, you don’t have to guess or overpay postage. Just set your envelope or package on the platform and you’ll instantly get the exact weight needed for rate calculations. Digital scales also make it easy to track weights of shipments and stay organized.
Additional Tips for Figuring Postage
- Write the weight directly on envelopes and packages so you have a record.
- Keep a postage price chart for common mailpieces for quick reference.
- Prepay postage online and print labels for packages instead of using stamps.
- Ask for assistance at the post office counter if you have any questions.
- Use Click-N-Ship on USPS.com to calculate and pay for postage.
- Sign up for USPS free shipping supplies to be delivered and save trips to the post office.
Determining the correct postage for mail may seem tricky, but just remember these key points:
- Letters and flats under 1 ounce = 1 forever stamp
- Heavier letters over 1 ounce require an additional stamp per extra ounce
- Packages and priority mail have zone-based rates based on weight
- Use USPS price calculators online to get exact rates
- Weigh mail on a digital scale for best accuracy
Following the size, distance, and weight guidelines for different mail classes will ensure you have enough stamps for delivery anywhere in the United States. Check the USPS website if you have any other questions about mailing services, postage prices, or sending packages.