No bounds checking to handle cases where the value is less than 0 or greater
than 500, but, assuming the value is in A1, try

=LOOKUP(1+INT(A1/150),{1,2,3;"OK","Check","Under"})

"carl" wrote:

I am trying to write a formula that will look at a value and if that value is
between 0 and 150 return "OK", if between 151 and 300. return "Check", or if
between 301 and 500 return "Under"

Thank you in advance.