Address Types
How to address a business envelope
Center the recipient name, title, company, and address block in the middle of a standard number 10 envelope, with the return address in the top left corner sized no larger than half the envelope length and a third of its height. For a window envelope, the letter itself has to be folded and printed so the address block lines up with the die-cut window, since there is no separate step of writing an address at all.
Checked July 30, 2026/7 min read
Written by Claire PostReviewed against USPS Publication 28
What is on this page6 sections
A business envelope looks like the most standardized, least interesting addressing situation on this site, and for a plain, non-window envelope, it mostly is: center the recipient, keep the return address within reasonable size limits, done.
A window envelope changes the entire problem. There is no address to write on the envelope at all. Instead, the letter itself has to be designed and folded so the right block of text lines up with a small die-cut opening, which is a formatting and folding problem far more than an addressing one, and it is the part of business mail that competitor guides consistently skip.
Step by step
Center the recipient block in the middle of the envelope
Name, title, company, then street address, then city/state/ZIP, each on its own line.
SARAH JOHNSON MARKETING DIRECTORWIDGET COMPANY INC456 OAK AVECHICAGO IL 60601CorrectStandard business envelope, addressed to a named contact. Keep the return address within size limits
Roughly half the envelope length and a third of its height at most, in the top left corner. A return address that runs larger than this can crowd the delivery address or the postage area.
Use a department name when you do not have a specific contact
Human Resources, Customer Service, or Accounts Payable work the same way a named individual would, and pair with an ATTN line the same way. See the full ATTN guide for the placement rule specifically.
Know that a window envelope is a different problem entirely
There is no separate addressing step for a window envelope. Instead, the letter itself is formatted so the address block, typically part of the letterhead or the inside address, lands exactly where the die-cut window exposes it once folded.
Fold the letter so the address sits inside the window with margin on all sides
A standard number 10 window envelope typically uses a letter folded in thirds, with the address block positioned so it sits centered in the window with roughly a quarter inch of clearance on every side once folded.
Quick reference
| Element | Rule |
|---|---|
| Standard #10 envelope size | 4-1/8 x 9-1/2 inches |
| Return address maximum size | 50% of length, 33% of height |
| Printed text margin | About 1/8 inch from any edge |
| Window envelope address | Positioned on the letter itself, not written on the envelope |
| No named contact available | Address the department instead |
Special cases
The rule above covers most people. Here is what changes for the rest.
How do I make sure the address lines up correctly in a window envelope?
Most word processors and letterhead templates position the inside address at a fixed distance from the top and left edges of the page specifically so it aligns with a standard window position once the letter is folded in thirds. If you are designing your own template, check the address block sits roughly one to one and a half inches from the top and left of the page, then do a test fold and hold it against an actual envelope before printing a full batch.
Does a window envelope still need a return address printed separately?
Yes. The window only handles the delivery address, pulled from the letter itself. The return address still needs to be either pre-printed on the envelope or added separately, the same as any standard envelope.
What if my business mail needs to go internationally?
The same window and sizing principles apply, but the address format itself needs to follow the destination country conventions rather than the standard US business format. See the international addressing guide for country-specific formats.
Key terms on this page
- Window envelope
- An envelope with a die-cut, often plastic-covered opening that shows the address printed on the letter inside, rather than requiring a separately written address.
- OCR scan zone
- The area of the envelope face where automated equipment expects to find and read the delivery address, relevant to keeping the return address and any other elements from overlapping it.
- Letterhead
- Pre-printed or templated business stationery that often includes the company name, logo, and sometimes a positioned address block designed to align with a window envelope.