Calculating CCA of a starter battery
No such formula exists.

The problem is that the current you can get from a battery is based on the exact temperature and details of the battery. Even if temperature is specified, the details of the battery construction vary. Different batteries that have the same voltage and same amp-hour capacity may have different cold cranking amp values.

Consider for example this: you may have 12V 45Ah deep cycle battery and 12V 45Ah starter battery. Which one of these would you expect to have higher CCA value? You probably guessed it correctly: the 12V 45Ah starter battery has a higher CCA value.

So, if the only thing you know is that the battery is 12V and 45Ah, you can't deduce the CCA.

You really need the datasheet of the battery!