Tips for large envelopes with USPS

When you are shipping products that require the use of large envelopes, it is common for questions to come up around charges due to size. As a service to your customers, it is important to make sure you are informed about any possible extra fees or restrictions.


A lot of USPS mail is subject to certain surcharges known as nonmachinable surcharges. These surcharges apply only when a letter cannot be automatically processed. USPS uses machines to automatically sort their letters and envelopes. If it can not sort them because of too much thickness or an odd bulge you will be charged. Since the USPS large envelopes have their own price structure, the nonmachinable surcharge will not affect you.

First-Class mail larger than letter size:

Many people think if a First-Class envelope is larger than letter-size that it will have to be over 1/4 inch thick to be priced as a large envelope. However, the 1/4 inch thickness is a guideline for the maximum thickness of letters and envelopes. Learn more about letter sizes with ShippingEasy's USPS size guide.

Typically, if your letter exceeds any of the measurement sizes for a letter it will be counted and priced as a large envelope. If it weighs more than or exceeds the large envelope sizes it may be subject to further price change.


If you are shipping your flat rate envelopes you do not have to worry about balloon rates or USPS dimensional weight since they work off a different price structure. Learn more about flat rate envelopes.


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