If you think there isn't much to know about folding a letter before putting it in the envelope, you're wrong. Especially when it comes to business letters, there are certain rules about how you should fold the letter. Therefore, before you put your letter in the envelope, take some time to learn about the different ways to fold a letter.
Steps
Method 1 of 3: Folding a standard business letter into a standard business envelope

Step 1. Describe the envelope
If you are handwriting the letter recipient's information on the envelope, do so before you put the letter in so you don't leave any marks on the letterhead.
- If you want your letter to look more professional, you can also print the address on the envelope.
- You must enter the address of the recipient on the front of the envelope in the middle (for example in the Netherlands: name, zip code, house number and city) and the address of the sender (your own name, zip code, house number and city) in the writing in the upper left corner.

Step 2. Place the letter face up on the table in front of you
Before folding the letter, check that the address on the letter matches the address on the envelope. Check again if you have signed the letter.
The text should be facing you, as if you are reading it

Step 3. Fold up the lower part of the letter
Take the bottom edge of the paper. Fold it up first and then down so that the bottom edge is about a third of the way up the paper.
If you're not sure how high that is, grab the envelope and use it as a guideline by placing it just below the center of the letter

Step 4. Check that the edges are aligned
Before folding the paper, make sure that the outer edges of the letter line up so you don't accidentally fold the letter crooked.
- If you don't fold the edges exactly at the right heights, you'll end up with a skewed letter and chances are it won't fit in the envelope.
- Once you are sure they are aligned, carefully fold the edges all the way in half with your fingers.

Step 5. Fold the top part down
Now take the top part of the letter and fold it down so that there is about 1 cm space between the bottom fold and the top (folded down) edge of the letter.
Even if you are not sure, use the envelope as a guideline. If the envelope is under the letter, you can check if the letter fits in the envelope by placing the top and bottom folds of the letter on top of the top and bottom of the envelope

Step 6. Now fold the top
Remember to line up the top part of the fold exactly with the edges of the page. That way you get a neat, straight fold.
You can hold a ruler horizontally between your fingers and slide the thin edge of the ruler along the paper so that you get a nice flat and straight fold

Step 7. Put the letter in the envelope
Take the letter so that the folds are facing out and the top fold is flush with the top of the envelope. Hold the envelope so that the flap of the envelope is facing you and opening toward you. Carefully place the letter in the envelope so that the edges of the paper do not fold or tear.
The recipient must be able to remove the letter from the envelope and open it without having to turn the letter over to read it
Method 2 of 3: Folding a standard business letter for a see-through envelope

Step 1. Make sure your letter is formatted correctly
If you're using an envelope with a see-through window that will show the recipient's name and address, it's very important that your letter is formatted correctly so that the information appears on the paper in exactly the right way.
- To properly format a business letter, first make sure that the margins on all sides are set to 2.5 cm in your word processing program. Make sure the text is aligned on the left side of the page and don't forget to type in the recipient's date and address.
- You should use single spacing throughout the letter, except between paragraphs. You should skip two lines between paragraphs. The entire letter should be aligned to the left.
- There should be about 5cm of space from the top of the paper to where you type the first line of text (the date).
- Write the date in full (so not 1/4/16, but 1 April 2016).
- Press enter twice to put a space between the date and where you type the recipient's information.
- Type the full name of the recipient (eg De Heer Jaap de Boer), tap enter and type in the recipient's address, tap enter again and enter the postal code, house number and city of the recipient.
- Remember to leave space between the recipient's contact information and the salutation.

Step 2. Fold the letter into a so-called z-fold
To properly use the see-through window of the envelope, fold the letter so that the recipient's name and address are facing out.
- This folding method is not as secure as folding a letter in, but you must fold it so that the name and address can be seen through the viewing window.
- If the letter contains sensitive information, it is best to use a standard envelope without a window.

Step #3. Start with the letter facing down so that the text is facing down
If the text is facing down, you can better see where the name and address are when you fold.
If you have done this correctly, you will not be able to read the text of the letter

Step 4. Lay the letter upside down
The letter should be face down, but at the same time, it should be so that the recipient's name and address are as close to you as possible.
If you've done this correctly, if you look at the paper at the bottom, the recipient's name and address will be on your side

Step 5. Fold the top down
Take the top third of the paper and fold it towards you.
If you're not sure how far that is, you can use the envelope as a guideline by placing it under the center of the paper

Step 6. Fold the bottom up
Take the bottom third of the paper and fold it up and away from you.
You should now see the name and address of the recipient

Step 7. Now put the folded letter in the envelope
Arrange the letter so that the recipient's information faces the front of the envelope. Place the letter in the envelope in such a way that the information is visible through the viewing window.
If you can't see the recipient's information, you probably put the letter upside down in the envelope. Remove the letter from the envelope and turn it over (with the recipient's information still pointing toward the viewing window)
Method 3 of 3: A standard business letter for a small business envelope

Step 1. Check the address
Before folding the letter, make sure that the address on the inside of the letter is the same as the one you wrote or printed on the envelope.
- That way you avoid sending letters to the wrong people.
- Do not forget to check whether you have signed the letter.

Step 2. Place the letter in front of you on the table or on your desk
Make sure the text is facing you and facing up. This is your last chance to review the letter and make sure you haven't forgotten anything.
For example, did you put the date above the letter? Are there no spelling or grammar mistakes?

Step 3. Fold the bottom half up
Take the bottom of the letter and fold it to about 1 cm from the top of the page.
As a guideline, you can place the envelope under the letter. When folded up, make sure the letter is small enough to fit inside the envelope

Step 4. Now fold the letter
Before folding the paper, make sure that the outer edges of the paper are all exactly together so that you don't get serif folds. A crooked fold can prevent the letter from fitting in the envelope.
Use a ruler to make the fold nice and sharp. You do this by holding a ruler horizontally and sliding the thin edge along the letter on the folds so that they become nice and tight

Step 5. Fold in the right half of the letter
Now take the right part of the letter and fold it inwards at about a third of the way of the paper.
Place the top and bottom edges of the letter on top of each other and only then fold the paper

Step 6. Fold in the left half of the letter
Take the other side of the letter and fold it inwards at the height of a third of the paper. This is done just like you did with the right side.
Line up the bottom and top edges of the paper so that they are exactly straight before folding them in half

Step 7. Turn the letter left or right and put it in the envelope
The last fold you made should be placed first, downwards, in the envelope. Place the letter in the envelope so that the folds point to the back.
This makes it easier for the recipient to see where to start unfolding the letter
Tips
- If you're using an envelope with an edge that you have to lick or otherwise moisten, make sure to moisten the edge from start to finish. Do not make it too wet, because then the edge will no longer stick properly.
- You can make the folded edges of your letter nice and sharp by flattening the folds completely with a ruler.
- Don't forget to put enough stamps on the letter before you send it.
- If you're putting a letter or greeting card in the envelope that's just folded in half, make sure the fold is at the bottom of the envelope. This prevents the recipient from accidentally tearing the letter in half with a letter opener.
- Read your letter carefully before putting it in the envelope. This way you can avoid embarrassing mistakes.