USPS Postage Calculator

Access the Absolute Lowest USPS Postage Rates with Shippo. Get Estimates with our USPS Postage Calculator.

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Get the Best USPS Postage Rates Available

With Shippo, you’re guaranteed to get the best possible postage rates from the USPS—no matter how many packages you ship. We negotiate with the USPS so that you can get the best rates, even those typically reserved for high-volume shippers. 

When you access the USPS through Shippo, you’ll save up to 90% compared to retail rates from the Post Office. And, since you can do everything online—including scheduling pickups from the USPS—you won’t spend any time waiting in line at the Post Office.

Getting started only takes a few minutes and is completely free. Unless you enjoy paying extra for postage or waiting in line at the Post Office, you’ve got nothing to lose.

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Compare USPS with UPS, FedEx, DHL, and More For Even Better Savings

In addition to the best USPS rates, Shippo also gives you direct access to deep discounts from UPS, FedEx*, and DHL of up to 62% off retail rates.

For every package you need to ship, Shippo makes it easy for you to compare rates and ETAs from all the carriers to make sure you get the absolute best option every time.

Note that due to contract restrictions, we can’t share rates from private carriers on the calculator above. Don’t worry. If you create a Shippo account, completely for free, you’ll be able to compare all carriers within our application.

*FedEx account required to access discounts.

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USPS First Class Package Service vs. First Class Mail: Are You Sending Packages or Letters?

USPS First Class is far and away the best option for sending items weighing less than one pound. 

USPS First Class Mail is for mailing postcards, letters, and large envelopes (also known as flats). To qualify, your envelope must be less than 13 ounces and not more than 15 inches long or more than 12 inches high or more than 3/4 inch thick; otherwise, you’ll use USPS First Class Package Service. Purchase First Class Mail postage from the USPS website or local Post Office directly. 

USPS First Class Package Service is the cheapest way to ship packages and poly mailers that are up to 15.999 ounces. 

There are several benefits to using Shippo to buy USPS First Class Package Service postage. First, Shippo’s rates are cheaper than the retail rates you’d pay through the USPS website or Post Office. Another benefit to using Shippo is that while the USPS website will sell you postage for packages weighing up to 13 ounces, Shippo extends that up to 15.999 ounces, so you can take advantage of the low rates for even heavier packages.

(Psst… looking to ship items weighing more than one pound? Check out our USPS shipping calculator.)  

Frequently Asked Questions

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How do I calculate USPS postage?

Enter the details of your package including its weight and dimensions, along with the origin and destination zip codes into the USPS postage calculator displayed above. You’ll then be able to access Shippo’s highly discounted rates. If you’d like to purchase labels with these discounted rates, just register for a Shippo account—it’s free.

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What are the benefits of using Shippo to purchase USPS postage?

By using Shippo, you get instant access to highly discounted USPS postage rates—up to 90% off the retail rates you’d pay at the Post Office or by purchasing through the USPS website.

On top of that, if you’re using the USPS First Class Package Service, you would be able to bypass the standard weight limitations of 13 ounces and now be able to ship packages up to 15.999 ounces. And, you would also gain access to the Priority Mail Cubic service level, which is an excellent cost-saving option for businesses shipping small, heavy items, as shipping rates are determined by package size and distance traveled, as opposed to package weight.

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What’s the largest BOX size I can SHIP WITH USPS?

With the USPS First Class Package Service, you can ship items up to 15.999 ounces in box sizes up to 22 inches (length) x 18 inches (width) x 15 inches (thickness). But, what if your packages are bigger? No worries. With Shippo, you get instant access to the best rates from USPS Priority Mail, which can accommodate packages up to 70 pounds, and 108 inches in total length and girth.

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What are USPS Commercial and Retail rates?

The term “Retail rate” refers to the actual cost a consumer pays if they purchase postage from their local Post Office or on the USPS website. “Commercial rates” are special discounted rates that businesses can access if they utilize a shipping software program such as Shippo.

Businesses will also gain extra benefits such as deep discounts on other USPS service levels, plus expanded weight limits on First Class Package Service shipments (from the maximum weight limit of 13 ounces, to 15.999 ounces.)

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Is it cheaper to send a box or envelope?

Since USPS First Class and Priority Mail set their postage rates by package weight and distance traveled, it does not matter whether you use a box or envelope. The only difference is that boxes tend to be heavier and may move your package up a weight class. The only time the size of the box (or envelope) matters is when you ship via USPS Priority Mail Cubic pricing. This is for packages weighing 1-20 pounds and about the size of a shoebox. In this instance, get the smallest box or envelope you can to ensure you’re getting the cheapest rate possible.

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What Is the Cheapest Way to Ship Internationally?

The USPS can be a very economical option for international shipping. Here is a list of the service options available:
• First Class Package International (light shipments)
• Priority Mail International (shipments over one pound)
• Priority Mail Express International (time-sensitive shipments)

*Rates are subject to change and do not include potential fees to use Shippo’s software (see pricing plans). Calculator does not include rates for First Class Mail.

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