Envelope Sizes You might be shopping for envelopes but that doesn't mean you're an expert. But after reading up on our envelope guides, you'll know everything there is to know! Our infographics go in detail about what every size envelope means - from their purpose, to what they are most popular for, from their flaps to which sizes cannot be mailed via USPS. When you desire for easy navigation and useful information about envelopes, our infographics will certainly help you out! Our Social and Invitation Envelope Size Guide will help you decide which envelope is perfect for your invitation, no matter the paper sizes. Whether you need a common envelope or specialty envelopes, we've got what you need. From A1 envelopes or mini envelopes(the smallest mailable size for US mail) or an A2 envelope for just a bit larger, to a10 envelopes or jumbo envelopes (perfect for oversized invites), to the a7 envelope which is perfect for invites, we have it all. Our Commercial and Business Envelope Size Guide will help you send out the perfect business mail. Our #10 Envelopes and window envelopes are the most common business envelope size, but our envelope collection doesn't stop there! Our last infographic is called? Promotional Mail Envelope Guide? and will help you understand the unique envelopes we offer. From Bubble Mailers to Photo Mailers and more, we will help you make sure what envelope fits best for all of your marketing and packaging needs. We weren't kidding when we said we have every color, every size and these infographics will certainly attest to our awesome slogan! So start learning and become an envelope expert today. Tweet