How many stamps per ounce?

Alex Cook's photo

By Alex Cook

The United States postal system is an incredible public service. For only $0.55, one can send a letter anywhere in the United States — including Alaska, Hawaii, and Puerto Rico — to arrive in 1-3 days!

Here are the most common stamps you’ll need per ounce when sending an envelope (known as “letters” by the USPS):

Weight Postage
Up to 1 ounce ($0.55) One Domestic Forever stamp ($0.55)
USA Forever Stamp, USA flag design
2 ounces ($0.70) One Domestic Forever stamp, and one 15¢ Additional Ounce stamp ($0.70)
USA Forever Stamp, USA flag designUSA additional ounce, 15 cent stamp, president heads wearing flag-themed tophats

Or you can overpay by $0.40 using two Domestic Forever stamps ($1.10)
USA Forever Stamp, USA flag designUSA Forever Stamp, USA flag design
3 ounces ($0.85) One Domestic Forever stamp, and two 15¢ Additional Ounce stamps ($0.85)
USA Forever Stamp, USA flag designUSA additional ounce, 15 cent stamp, president heads wearing flag-themed tophatsUSA additional ounce, 15 cent stamp, president heads wearing flag-themed tophats

Or you can overpay by $0.25 using two Domestic Forever stamps ($1.10)
USA Forever Stamp, USA flag designUSA Forever Stamp, USA flag design
3.5 ounces ($1.00) One Domestic Forever stamp, one 35¢ Postcard stamp, and one 10¢ stamp ($1.00)
USA Forever Stamp, USA flag designUSA Postcard 35 cent stamp, brown shell with teal backgroundUSA 10 cent stamp, two red pears reading 10¢ in the upper left and USA in the bottom right, in red font

Or you can overpay by $0.10 using two Domestic Forever stamps ($1.10)
USA Forever Stamp, USA flag designUSA Forever Stamp, USA flag design
More than 3.5 ounces See table below

Use a kitchen food scale to measure your envelope’s weight. If you don’t own one, Amazon makes a good entry level scale for $10.99 and there’s a higher end scale from My Weigh for $38 on Amazon Prime. Walmart also offers several cheap kitchen scales like this Milleroo scale for $8.25

Square envelopes

If you’re sending a square envelope, add an additional $0.17 to your envelope and make sure it’s a minimum of 5″. You can buy $0.02 stamps from the post office.

Add $0.17 for rigid envelopes and other gotchas

In general, the above guidelines apply to standard letters that are rectangular, up to 3.5 ounces, and bendable. If you have an envelope that doesn’t bend (rigid) or isn’t a uniform thickness (check out the USPS First Class Mail Fact sheet for a full list of “nonmachinable” characteristics), add the additional $0.17.

Sending more than 3.5 ounces or sending large envelopes

If you’re sending more than 3.5 ounces, you’re required to use a large envelope (known by the USPS as a “flat.”). The maximum weight is 13 ounces. Your envelope must be a minimum of  6 1/8″ x 11 1/2″, maximum 12” x 15”. A standard 8.5” x 11” manilla envelope is the most common and good to have handy. You can pick up a 100 pack on Amazon for $15.99 ($0.16 each) or 20 pack for $4.83 ($0.24 each). Local office supply stores also have these. Staples offers a 100-pack for $40.79 ($0.41 each).

Note that the same envelope rules (can’t be rigid, must be uniform, etc) from above apply to flats; when in doubt, add $0.17.

Weight Postage
Up to 1 ounce ($0.80) One Domestic Forever stamp, one 15¢ Additional Ounce stamp, and one 10¢ stamp ($0.80)
USA Forever Stamp, USA flag designUSA additional ounce, 15 cent stamp, president heads wearing flag-themed tophatsUSA 10 cent stamp, two red pears reading 10¢ in the upper left and USA in the bottom right, in red font

Or you can overpay by $0.30 using two Domestic Forever stamps ($1.10)
USA Forever Stamp, USA flag designUSA Forever Stamp, USA flag design
2 ounces ($0.95) One Domestic Forever stamp, one 35¢ Postcard stamp, and one 5¢ stamp ($0.95)
USA Forever Stamp, USA flag designUSA Postcard 35 cent stamp, brown shell with teal backgroundUSA five cent stamps, two bundles of purple grapes with green leaves, reading 5¢ in the upper left and USA in the bottom right, both in purple font

Or you can overpay by $0.15 using two Domestic Forever stamps ($1.10)
USA Forever Stamp, USA flag designUSA Forever Stamp, USA flag design
3 ounces ($1.10) Two Domestic Forever stamps ($1.10)
USA Forever Stamp, USA flag designUSA Forever Stamp, USA flag design
4 ounces ($1.25) Two Domestic Forever stamps, and one 15¢ Additional Ounce stamp ($1.25)
USA Forever Stamp, USA flag designUSA Forever Stamp, USA flag designUSA additional ounce, 15 cent stamp, president heads wearing flag-themed tophats

Or you can overpay by $0.40 using three Domestic Forever stamps ($1.65)
USA Forever Stamp, USA flag designUSA Forever Stamp, USA flag designUSA Forever Stamp, USA flag design
5 ounces ($1.40) Two Domestic Forever stamps, and two 15¢ Additional Ounce stamps ($1.40)
USA Forever Stamp, USA flag designUSA Forever Stamp, USA flag designUSA additional ounce, 15 cent stamp, president heads wearing flag-themed tophatsUSA additional ounce, 15 cent stamp, president heads wearing flag-themed tophats

Or you can overpay by $0.25 using three Domestic Forever stamps ($1.65)
USA Forever Stamp, USA flag designUSA Forever Stamp, USA flag designUSA Forever Stamp, USA flag design
6 ounces ($1.55) Two Domestic Forever stamps, one 35¢ Postcard stamp, and one 10¢ stamp ($1.55)
USA Forever Stamp, USA flag designUSA Forever Stamp, USA flag designUSA Postcard 35 cent stamp, brown shell with teal backgroundUSA 10 cent stamp, two red pears reading 10¢ in the upper left and USA in the bottom right, in red font

Or you can overpay by $0.10 using three Domestic Forever stamps ($1.65)
USA Forever Stamp, USA flag designUSA Forever Stamp, USA flag designUSA Forever Stamp, USA flag design
7 ounces ($1.70) Three Domestic Forever stamps, and one 5¢ stamp ($1.70)
USA Forever Stamp, USA flag designUSA Forever Stamp, USA flag designUSA Forever Stamp, USA flag designUSA five cent stamps, two bundles of purple grapes with green leaves, reading 5¢ in the upper left and USA in the bottom right, both in purple font

Or you can overpay by $0.50 using four Domestic Forever stamps ($2.20)
USA Forever Stamp, USA flag designUSA Forever Stamp, USA flag designUSA Forever Stamp, USA flag designUSA Forever Stamp, USA flag design
8 ounces ($1.85) Three Domestic Forever stamps, one 15¢ Additional Ounce stamp, and one 5¢ stamp ($1.85)
USA Forever Stamp, USA flag designUSA Forever Stamp, USA flag designUSA Forever Stamp, USA flag designUSA additional ounce, 15 cent stamp, president heads wearing flag-themed tophatsUSA five cent stamps, two bundles of purple grapes with green leaves, reading 5¢ in the upper left and USA in the bottom right, both in purple font

Or you can overpay by $0.35 using four Domestic Forever stamps ($2.20)
USA Forever Stamp, USA flag designUSA Forever Stamp, USA flag designUSA Forever Stamp, USA flag designUSA Forever Stamp, USA flag design
9 ounces ($2.00) Three Domestic Forever stamps, and one 35¢ Postcard stamp ($2.00)
USA Forever Stamp, USA flag designUSA Forever Stamp, USA flag designUSA Forever Stamp, USA flag designUSA Postcard 35 cent stamp, brown shell with teal background

Or you can overpay by $0.20 using four Domestic Forever stamps ($2.20)
USA Forever Stamp, USA flag designUSA Forever Stamp, USA flag designUSA Forever Stamp, USA flag designUSA Forever Stamp, USA flag design
10 ounces ($2.15) Three Domestic Forever stamps, one 35¢ Postcard stamp, and one 15¢ Additional Ounce stamp ($2.15)
USA Forever Stamp, USA flag designUSA Forever Stamp, USA flag designUSA Forever Stamp, USA flag designUSA Postcard 35 cent stamp, brown shell with teal backgroundUSA additional ounce, 15 cent stamp, president heads wearing flag-themed tophats

Or you can overpay by $0.05 using four Domestic Forever stamps ($2.20)
USA Forever Stamp, USA flag designUSA Forever Stamp, USA flag designUSA Forever Stamp, USA flag designUSA Forever Stamp, USA flag design
11 ounces ($2.30) Four Domestic Forever stamps, and one 10¢ stamp ($2.30)
USA Forever Stamp, USA flag designUSA Forever Stamp, USA flag designUSA Forever Stamp, USA flag designUSA Forever Stamp, USA flag designUSA 10 cent stamp, two red pears reading 10¢ in the upper left and USA in the bottom right, in red font

Or you can overpay by $0.45 using five Domestic Forever stamps ($2.75)
USA Forever Stamp, USA flag designUSA Forever Stamp, USA flag designUSA Forever Stamp, USA flag designUSA Forever Stamp, USA flag designUSA Forever Stamp, USA flag design
12 ounces ($2.45) Four Domestic Forever stamps, one 15¢ Additional Ounce stamp, and one 10¢ stamp ($2.45)
USA Forever Stamp, USA flag designUSA Forever Stamp, USA flag designUSA Forever Stamp, USA flag designUSA Forever Stamp, USA flag designUSA additional ounce, 15 cent stamp, president heads wearing flag-themed tophatsUSA 10 cent stamp, two red pears reading 10¢ in the upper left and USA in the bottom right, in red font

Or you can overpay by $0.30 using five Domestic Forever stamps ($2.75)
USA Forever Stamp, USA flag designUSA Forever Stamp, USA flag designUSA Forever Stamp, USA flag designUSA Forever Stamp, USA flag designUSA Forever Stamp, USA flag design
13 ounces ($2.60) Four Domestic Forever stamps, one 35¢ Postcard stamp, and one 5¢ stamp ($2.60)
USA Forever Stamp, USA flag designUSA Forever Stamp, USA flag designUSA Forever Stamp, USA flag designUSA Forever Stamp, USA flag designUSA Postcard 35 cent stamp, brown shell with teal backgroundUSA five cent stamps, two bundles of purple grapes with green leaves, reading 5¢ in the upper left and USA in the bottom right, both in purple font

Or you can overpay by $0.15 using five Domestic Forever stamps ($2.75)
USA Forever Stamp, USA flag designUSA Forever Stamp, USA flag designUSA Forever Stamp, USA flag designUSA Forever Stamp, USA flag designUSA Forever Stamp, USA flag design

Where to apply stamps on a letter

Stamps should go in the upper-right corner of the envelope. In general, it’s best to apply them in a single, horizontal row. However, the USPS will generally accept a letter even if your stamps carry to a second row.

Mailing printed photos? Check out our guide on how many stamps to use per photo.