Envelopes are simple… right?
In theory, it seems like buying envelopes would be an easy task. But when you’re the person responsible for ordering office supplies at the office or for your own small business, deciphering the differences between number 8, 9 or 10 envelopes is not always so intuitive.
Does the “10” in no. 10 envelope stand for 10 inches? If there’s a number 10 envelope, is there a 20? The answers here are no and no – but we definitely understand the confusion!
So in this post, we’re answering the most frequently asked questions about the no. 10 envelope size to make selecting the right envelope for your needs a simpler process.
We often get asked for the measurements of this most popular business envelope. Envelope sizes are always listed by the shortest dimension first, which for standard business envelopes is the height. The second measurement always equals the longer edge of the envelope, or the width.
Using this format, the standard number 10 envelope size is generally accepted as 4-1/8 inches tall x 9-1/2 inches wide. Those are the dimensions of the #10 envelopes that we sell here at Blue Summit Supplies; while there is no law dictating that number 10 envelopes to be this precise size, most envelope manufacturers use these standard dimensions as a general rule of thumb.
For our math-illiterate friends (we know you’re out there, and it’s okay), a sheet of standard white letter paper folded in thirds, trifold style (sometimes more affectionately known as “hot dog style”) fits easily inside a number 10 envelope.
In the business world, the #10 envelope is best for mail printed on standard 8 ½ x 11 in. sheets of letter paper – the size of white copy paper. Things like monthly statements, bills, invoices, and other business correspondence are often mailed in no. 10 envelopes.
And transactional mail – mail requiring an action from the receiver – usually is sent in number 10 envelopes because a return mail envelope fits inside. Return business mail envelopes are typically smaller #8 or #9 envelopes, which mailed inserted inside the larger #10 envelope.
Just like most business envelopes, #10 envelopes are available both with and without windows. #10 envelopes with single windows are typically used to display the recipient’s mailing address through the window opening. The sender can then either inscribe a handwritten return address, use a return address label, or have their envelopes pre-printed with their return address.
Alternately, double window #10 envelopes are designed so that both the recipient and return addresses can be seen through the windows. Most often, these mailing addresses are pre-printed on the business correspondence inside, then folded so that they conveniently show through the envelope windows – with no additional labels or handwriting addresses required.
We’ve created a few free templates to help you print letters using the standard window options for the number 10 envelope size. After all, fit matters. Just ask Larry – she knows firsthand that using the right size envelope is important when it comes to both professionalism and privacy.
(Looking to print directly on an envelope? Microsoft Office offers detailed instructions for how to do this in Word right here.)
We know how frustrating it can be to find the best size envelopes for checks or invoices printed with QuickBooks so that your address information lines up correctly in the windows. While #10 windowed envelopes do work great for QuickBooks invoices, we don’t recommend using them for QuickBooks checks. If a #10 envelope is used to send QuickBooks checks, it is likely that the address window will reveal the check amount through the bottom window. Instead of using a #10 envelope for QuickBooks checks, we recommend using a #8 envelope – particularly one with windows that were designed specifically to align with QuickBooks checks. Click here for a few options!
As with most envelopes, the key differences (other than size) often come down to the types of seals. It's standard to find both windowless and windowed envelopes with each of the three most standard kinds of envelope seals: gummed, self-seal, and flip and seal. We have a more in-depth piece about envelope seals here, or you can reference the handy breakdown below.
Envelopes sound so simple and boring on the surface – but we know it’s not always so easy. Business mail needs can be complex; mailings range from simple letters to multi-page invoices to confidential billings. Therefore, you need envelopes on hand to fit those specific needs and measurements – and we’d like to help make that process as easy as possible.
As always, our Chief Happiness Officer Larry is here to answer any additional questions you might have about number 10 envelopes (or any other size). Feel free to leave her a comment below or shoot an email to larry@bluesummitsupplies. She or one of her Happiness Agents will get on the case ASAP!
Thanks for your comment! Please note that comments are reviewed before showing up.