How to Mail Large Envelopes

Michael Blann/Photodisc/Getty Images

When your business is mailing a large envelope with documents, magazines or flat merchandise, the United States Postal Service has options ranging from regular First-Class Mail using stamps to expedited Priority Mail services with flat-rate postage options. Depending on the service chosen, you may pay a special rate for large envelopes or the usual package pricing by weight and location. USPS offers a handy calculator so you can know your exact large envelope postage and the multiple options for sending the item.

Basics of Large Envelopes

The USPS website classifies a large envelope as one meeting these requirements:

  • Rectangular
  • Square corners
  • Height between 6 1/8 and 12 inches
  • Length between 11 1/2 and 15 inches
  • Uniform thickness between 1/4 and 3/4 of an inch

Weight restrictions will also apply and depend on the service level used. Like with mailing packages, you can also often add insurance or use Certified or Registered Mail for valuable or confidential documents and items.

Using First-Class Mail

Using USPS First-Class Mail will get your large envelope of up to 13 ounces to the domestic destination within three business days.

Currently, the retail rate starts at $1.00 for a 1-ounce large envelope, and you'll pay 20 cents extra per ounce beyond that; this means a maximum of $3.40 for a 13-ounce large envelope. The commercial rates depend on the presorting type used and start as low as 43 cents for a 1-ounce large envelope with 20-cent increments used for each additional ounce.

For your convenience, you can stick multiple Forever Stamps worth 55 cents each along with smaller stamps to cover the postage. You can also have the item weighed at a post office or use your own metered mail service for this option.

Using Priority Mail and Priority Mail Express

When you have more urgent mail to send, you can use Priority Mail Express for overnight delivery or Priority Mail for delivery within three business days. Priority services automatically come with $50 of insurance and have optional flat-rate envelopes you can use. Your envelope can weigh up to 70 pounds, and you'll typically use metered postage or printed shipping labels rather than stamps for this option.

Flat-rate envelopes for Priority Mail begin at $7.75 for the retail rate and $7.02 for the commercial rate. For Priority Mail Express, they start at $26.35 for the retail rate and $22.75 for the commercial rate.

When you use your own envelope, you pay depending on the postal zone and envelope weight. A 1-pound large envelope can cost anywhere between $7.50 and $14.05 with Priority Mail and between $26.75 and $59.90 with Priority Mail Express at the retail rates. The same 1-pound envelope using commercial pricing could range from $7.02 to $11.40 for Priority Mail and $23.00 to $51.60 for Priority Mail Express.

Getting Your Exact Envelope Postage

If you're not using a postage meter to determine exact pricing, try the USPS postage calculator listed in the website's "Quick Tools" menu. You'll be able to enter information about the destination and mailing location to get both estimated delivery dates and pricing details for all mailing services available for your large envelope.

If you plan to use a flat-rate USPS envelope, you'll select that option; otherwise, select the option to calculate depending on your package size. Estimate your envelope's weight if the calculator asks you and specify that you're using a large envelope that meets USPS requirements.

Once you see service and price options, you'll also know whether you can buy and print postage through the USPS website for your convenience. You can use stamps for First-Class large envelopes and visit a postal location for any of the service levels.

Mailing Large Envelopes (Flats)

Once you have your large envelope postage and are ready to mail it, you can often simply drop it in a collection box as long as it's 10 ounces or less and not thicker than half an inch. You can schedule free USPS pickups for Priority Mail and Priority Mail Express items, and you can include a First-Class large envelope as long as you have an expedited item too. You can also simply take the large envelope to a postal location.