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