If you are attempting to design any item on Letter size paper to fit correctly inside of a #9 Double Window Envelope, then my overly detailed approach is the solution for your probably google search.

I didn’t have this kind of luck when I searched Google. You guys have it sooooo easy.

The return window should begin 0.7875″ from the top of the page and 0.5625″ from the left edge of the page.

It should be 1″ tall, and 3.125″ wide. The logo and return address should be completely within this boundary.

The Address window should be 2.2125″ from the top of the page and 0.5625″ from the left edge of the page.

It should be .8″ tall, and 3.625″ wide and the address of the doctor should rest firmly within it.

These measurements allow for an invoice to rest inside a standard #9 Double Window Envelope whether the letter/invoice/statement shifts to the left, right, top, or bottom.

You’re welcome.