How Many Stamps For 5 Ounces? (All You Need To Know)

One of the greatest intricacies of the United States Postal Service is figuring out how much postage you need for a smaller, lighter mailpiece. There is some overlap between First-Class letters and Flats and First-Class Package mail classes where weight is involved.

But say you want to mail a five-ounce parcel with stamps? How many stamps for a five-ounce parcel, you wonder? Luckily the Postal Service is straightforward about pricing. Here’s the answer you seek!

How Many Stamps For 5 Ounces In 2024?

The United States Postal Service’s First-Class individual Forever stamp price is $0.58; thus, four Forever stamps would cover the $1.96 in postage needed in 2024. However, that would exceed the required amount. A fully accurate amount of postage would involve three Forever stamps, one $0.20 additional ounce stamp, and a $0.02 stamp.

To learn how I arrived at this calculation, how much postage you would need for a five-ounce envelope, and even some other mail classes that could cover a five-ounce mailpiece, keep going!

How Do You Calculate How Many Stamps You Need?

When you are using stamps as postage (as opposed to printed shipping labels), you signify using First-Class mail.

That said, First-Class letters and Flats mail come with certain stipulations regarding how postage works.

For example, a First-Class letter mail must weigh less than an ounce and fit within the sizing parameters for one Forever stamp to meet the postage need. These sizing parameters are:

  • Minimum: ⅗ inches high; 5 inches long; .007 inches wide
  • Maximum: 6 ⅛ inches high; 11.5 inches long; 1/4-inch thick

Also, if the envelope meets the measurements but is heavier than an ounce, additional postage is needed.

  • Up to two ounces requires $0.78 worth of postage
  • Up to three ounces requires $0.98 worth of postage
  • Up to 3.5 ounces requires $1.18 worth of postage

You can see that each additional ounce warrants another $0.20 worth of postage. In comparison, Flats’ sizing parameters are:

  • Minimum: 6 ⅛ inches high; 11.5 inches long; 1/4-inch thick
  • Maximum: 12 inches high; 15 inches long; 3/4-inch thick

Any bigger than that or heavier than 13 ounces, you have a package that is no longer eligible for First-Class shipping.

Now, for envelopes that qualify as Flats, the post office calculates like this:

  • One ounce: $1.16
  • Two ounces: $1.36
  • Three ounces: $1.56
  • Four ounces: $1.76
  • Five ounces: $1.96

And so on, adding $0.20 per ounce until you hit the max weight of 13 ounces (the max price being $3.56).

How Do You Calculate How Many Stamps You Need? USPS

Therefore, knowing the scale on which a letter and a Flat can be measured and priced, you can calculate postage on your own.

Further, a letter-sized envelope that weighs 3.2 ounces would require $1.18 in postage. But, with Forever stamps worth $0.58 in postage, you could “overpay” with three of those.

Or, if you have small postage on hand or don’t mind a trip to the post office, you can use two Forever stamps ($1.16 total) plus a $0.02 stamp.

How Much Does It Cost To Mail 5 Ounces?

If you have an item that weighs five ounces, whether it fits into a regular envelope, a large envelope, or even a small box, you have options for shipping it beyond First-Class.

Of course, if you want to go the First-Class route, the price is $1.96, and you can use Forever stamps (and overpay) or a combination of Forever and other stamps.

But what if you’re in a hurry? Important legal documents? Something you promised your cousin for their show-and-tell at school, and it’s in two days?

Well then, by all means, you can use other mail classes, like Priority Mail or Priority Mail Flat-Rate.

With that, Priority Mail for an item under one pound starts at $8.70 for local and Zones 1 and 2 and maxes out at $19.40 for Zone 9.

On the other hand, Priority Mail Flat Rate envelopes cost just $8.95, regardless of Zone.

Also, if your item qualifies as a Flat, that likely means it would fit in a Priority Mail Express Flat-Rate envelope.

Additionally, Priority Mail Express envelopes cost $26.95 to ship, regardless of Zone – with the benefit of next-day or two-day delivery guaranteed (or your money back).

Or, you might opt for USPS Retail Ground, which starts at just $8.50 and only maxes out at $10.25 for Zone 9 for packages less than one pound.

You can find all the price charts for these shipping options here, plus the Zone map here and the Postage Price Calculator here.

To learn more, you can also read our posts on USPS stamp types, do USPS stamps expire, and USPS 70 cent stamps.


When an envelope is heavier than four ounces, it technically qualifies as a Flat, which costs $1.96 to mail via First-Class.

That requires four Forever stamps (which is overpaying), or three Forever stamps, a $0.20 extra-ounce stamp, and a $0.02 stamp for exact postage.

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Cara Suppa

Cara Suppa has been freelance writing for over a decade and holds a BA in English and an MS in Integrated Marketing Communications. Outside of work, she is an avid cook, gardener, and discount shopper.

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