IF Formula for amount of Characters in a Cell

I need an IF formula or maybe even another logic formula value that will display one of two values (acceptable, unacceptable) if a cell had a set number of characters.

Example Scenario:
I have 4 cells that require the following:
Cell B1 requires 9 charachters
Cell B2 requires 16 characters
Cell B3 requires 20 characters
Cell B4 requires 10 characters

I want Cells C1 - C4 to display Acceptable or Unacceptable based on the amount of characters in cells B1 - B4 (if there are 5 characters in B1, C1 should display unacceptable)

Note: Can C1- C4 also contain a Conditional Format (when its acceptable the cell is green and if its unacceptable the cell is red, both with a white font for visibility).

Re: IF Formula for amount of Characters in a Cell

Thank you (Wigi, Max, and Bob)
I used a combination of the Data Validation and LEN to accomplish my goal.

thank you so much for your help. again.

Re: IF Formula for amount of Characters in a Cell

Max, To answer your question "Why allow unnacceptable char length however?" the some values hard values that I don't want the user to enter anything more or less than the required and I used the Data Validation, in one specific area I want to allow the user to enter any value but be shown the values is not the correct length.

Thanks again.