Character Count in a 'cell' based on a Letter

I need to create 2 functions in the same column, they are;

Product numbers: Characters greater than 12 = Bold/Red Font
Product numbers: Characters starting with the letter 'K' and is greater than 16 = Highlighted Cell

Purpose: Product numbers are entered into a database with these requirements

I understand Conditional formatting and the LEN function but I am unable to apply both functions using either successfully? Is this reasonable request in Excel?

Tlazio

All Product numbers MUST remain in the same column.

Product numbers beginning with the letter 'K' (or K0) may contain up to, but no more than, 16 characters.
All other Product numbers can contain up to, but no more than, 12 characters.

TP21-1/0 (8 char. okay)
HLP322MTS-20 (12 char. okay)
HLP322MTSL-20 (13 char. not allowed)

K0TPCABLE-3-24 (14 char. okay)
K0TPCALABEL-3-24 (16 char. okay)
K0TPCALABELS-3-24 (17 char. not allowed)

Hope this helps.

Tlazio

Thank you shg!

Although this works fine, the workbook should not contain another column as listed above. Also, the cells are compiled by other users and they need to see when the data does not fit the criteria so that it can be corrected prior to moving it on. So, what I'm looking for in this formula is to highlight the cells that contain more than the allotted characters for each scenario. Can this be done without adding another column?

Tlazio

Or try this ...

=LEN(A1)<17-4*(LEFT(A1)<>"K")