Microsoft Word has generally offered a special tool for printing on envelopes, however the design of this tool and its facility with printing has changed across various versions of the application. Therefore, it’s important to understand the basic functions of setting paper size and orientation.

Width x Height

Suppose you’re planning to print on a #16 Bankers Flap Envelope. Which side is longer? The industry describes this medium as 6″ x 12″, but you can measure either side first. Just make sure you set the orientation to match how you’ll feed the envelope into your printer.

Orientation

Which way is up? In the above example, if you plan to feed the envelope’s short edge and you think of the wide envelope as a landscape orientation, then you must set the width to the shorter dimension (6″) and the height to the longer (12″).

This may seem counterintuitive but otherwise, you may end up printing addresses 90° askew. The only way to measure the long dimension as the width and think of it as the lateral measurement is to set a portrait orientation for this setup.

Skip the Envelopes Tool

If you just want to print one envelope and don’t need to use mail merge to print a bunch, I would skip the tool altogether. Instead, create a custom paper size and use separate text boxes for the destination and return addresses.

You don’t even have to use Microsoft Word. Use any word processor or page layout app that supports placing text on a page and use the wisdom above to set proper dimensions.

One additional sticking point when printing envelopes: You generally want a rear/manual feed slot in your printer. This prevents the envelopes from curling while they approach the print head and keeps them flatter on exit. Some units only offer a cassette underneath and may not be suitable for envelope jobs.