How to Fold a Letter into an Envelope

What You’ll Need

A standard sheet of paper (8.5 x 11 inches or A4)
A business envelope (No. 10 or similar)
A flat, clean surface to work on

Step-by-Step

Place the paper face down. Lay the letter on a flat surface with the text facing down and the top edge toward you. This ensures the fold lines are on the back of the letter, keeping the front clean.
Fold the bottom edge up. Take the bottom edge of the paper and fold it upward so it meets the top edge, but leave a small gap (about 1/2 inch or 1 cm) between the bottom edge and the top edge. This gap prevents the letter from being too tall for the envelope.
Crease the bottom fold. Press firmly along the fold with your fingers or a bone folder to create a sharp crease. A sharp crease makes the letter thinner and easier to insert.
Fold the top edge down. Now take the top edge of the paper and fold it downward so it meets the bottom fold you just made. The top edge should align exactly with the crease of the bottom fold.
Crease the top fold. Press firmly along this second fold to create a sharp crease. You should now have a rectangle that is roughly one-third the height of the original sheet.
Insert into the envelope. Hold the envelope with the flap facing up and the opening toward you. Slide the folded letter into the envelope with the open edges (the folds) facing the bottom of the envelope. The last fold (the one you made in step 4) should be at the top, so the recipient can pull it out easily.

Common Mistakes

Folding the paper in half: A half-fold is too wide for a standard envelope and will look bulky. Always use the tri-fold method.
Not leaving a gap: If you fold the bottom edge exactly to the top, the letter will be too tall and may bulge or tear the envelope.
Inserting the letter with the wrong side up: If you insert the letter with the text facing the back of the envelope, the recipient will see the back of the letter when they open it. Always insert with the text facing the back of the envelope (so the front of the letter faces the front of the envelope).
Not creasing sharply: A soft crease makes the paper thicker and harder to insert, and it may pop open inside the envelope.

Tips

Use a bone folder or the edge of a ruler to get a crisp crease.
If you’re mailing multiple pages, fold them together as one stack, but make sure the top page is on top and the text is facing up before folding.
For window envelopes, fold the letter so the address appears in the window. Usually, you fold the letter in thirds but position the address so it shows through the window.
If the paper is thick (like cardstock), consider using a larger envelope or folding it in half instead of thirds.
Always test-fit the letter in the envelope before sealing, to avoid having to refold.

Troubleshooting

The letter is too big for the envelope: Check if you left the gap in step 2. If not, refold with a larger gap. If the paper is too thick, use a larger envelope.
The letter pops open inside the envelope: This happens when the folds are not sharp enough. Refold with a bone folder or press harder.
The address doesn’t show through the window: Fold the letter so the address is on the front side (the side that will face the front of the envelope). You may need to adjust the fold position.
The letter is wrinkled: If the paper is wrinkled, it will not fold neatly. Use a fresh sheet or iron it on low heat (no steam) before folding.

Frequently Asked Questions

Can I fold a letter into a square envelope?

Yes, but you’ll need to fold the paper to fit the square dimensions. Typically, you fold the paper in half horizontally, then in half vertically, to create a smaller rectangle that fits.

How do I fold a letter for a window envelope?

Fold the letter in thirds, but position the address so it appears in the window. Usually, you fold the bottom up first, then fold the top down, and the address should be on the front side (the side that faces the front of the envelope).

What if my letter is longer than one page?

Stack the pages in order, with the first page on top. Fold the entire stack as one unit. Make sure the top page is facing up and the text is oriented correctly.

Should I fold the letter with the text facing up or down?

Fold with the text facing down. This puts the fold lines on the back of the letter, so the front looks clean when the recipient opens it.

How do I fold a letter to fit a small envelope?

For a small envelope, you may need to fold the paper in half first, then fold it in thirds, or even fold it into quarters. Measure the envelope and adjust the folds accordingly.

Is it okay to fold a letter more than three times?

Yes, if the envelope is small, you can fold the letter into quarters or even smaller. Just make sure the folds are sharp and the letter fits without bulging.

Sources: USPS. Menus and buttons can differ slightly by version. Spotted something out of date? Tell us.