What size is a #10 envelope? What size is a #9 reply envelope? What size enclosure can I put in a #10 envelope?

At 3rd Coast Imaging, we get questions about envelope sizes all the time. Our printing services include envelopes and letterhead, event invitations, and other projects that require some knowledge of proper sizing. For your reference, we have provided the common business envelope sizes and the recommended maximum sizes for inserts:

Number Width Height Enc. Width Enc. Height
#5 Envelope 5.50 3.06 5.50 2.81
#6 Envelope 6.00 3.38 5.75 3.13
#6 1/4 Envelope 6.00 3.50 5.75 3.25
#6 1/2 Envelope 6.25 3.56 6.00 3.31
#6 3/4 Envelope 6.50 3.63 6.25 3.50
#7 Envelope 6.75 3.75 6.50 3.50
#7 1/2 Envelope 7.63 3.75 7.38 3.50
#7 3/4 Monarch) Envelope 7.50 3.88 7.25 3.63
#8 5/8 (Check) Envelope 8.63 3.63 8.38 3.38
#9 Envelope 8.88 3.88 8.63 3.63
#10 Envelope 9.50 4.13 9.25 3.88
#10 1/2 Envelope 9.50 4.50 9.25 4.26
#11 Envelope 10.38 4.50 10.13 4.25
#12 Envelope 11.00 4.75 10.75 4.50
#14 Envelope 11.50 5.00 11.25 4.75

 

There are other factors to take into account when executing a mailing project, such as the cost of postage (check out the USPS’s Sizes for Letters info to determine what rate you’ll pay), setting up your files correctly using an envelope templates, and thinking about how many colors you’ll want to print in, which also has an effect on cost.