## Presentation of the LEN function

The **LEN** function returns the number of characters in a cell. It's simple 😉

=LEN(string)

**And that's all? 🤔🤨**😲

Yes, that's all! But this function is very useful for logical tests or for conditional formatting

## Remarks

If you have a string containing a comma, point, dash, space, etc. the **LEN function counts every character**.

For instance, in this picture, you have a **different way to write the same string** (GivenName) and the function** LEN returns a different result** for each row.

Now, look carefully at the result of **cells A2 and A3.**

**They look the same** but the result is different because **the string length is not the same**. 🤨🤔

This is because **there is a space at the end of the last cell**. You can remove it easily with the TRIM function.

## Check if an ID is correct

Let's say you have a list of IDs (customer ID, Product ID, ...). Each ID has the same length and you want to check if all your codes have the correct length.

In our example, a product code **must have 12 digits**.

We can use the function like this

=LEN(A2)

But seriously, **it's impossible to find in a blink of an eye which cell is correct or not**. So let's create a logical test 😃

## Insert the function in a logical test

We can easily convert the previous formula into a test just by adding the expected result, like this:

=LEN(A2)=12

Don't be surprised by the two = signs. You will find the explanation in this article.

## Invert the test

Well in this example, **we don't care if the length is correct.** What we want is to have the result return TRUE when the length is not equal to 12.

We can write is like this:

=LEN(A2)<>12

Or like this:

=NOT(LEN(A2)=12)

## Insert a logical test into an IF function

To customize the result of the test, we insert the test into an IF function, like this:

=IF(LEN(A2)<>12,

Now what's happen if the test is TRUE? Well, we just return a message (Not correct). And if the test is FALSE (the length is correct), we return nothing:

=IF(LEN(A2)<>12,"Not correct","")

That's much better but we can improve the result by **showing the length when the test is TRUE**:

=IF(LEN(A2)<>12,LEN(A2),"")

**Or the gap** between the correct length and the actual length:

=IF(LEN(A2)<>12,LEN(A2)-12,"")

Our test is now finished and we can see immediately which cell is not correct 😃😍😍