each cell have same number of charaters

[htown]

I need to ensure each cell has 8 characters throughout a column .

 

[Gary''s Student]

If we already have data in column A, then in B1 enter:
=IF(LEN(A1)=8,"","bad length")

and copy down. This will reveal bad items

If data is being entered into column A, then just use Data Validation:

Data... > Validation... > Custom > Formula > =len(A1)=8

 

[Don Guillett]

You are very UN clear about your need so I'll guess it's numbers and you
want to custom format
00000000