There are different rules in every state. Depending on the state you are divorcing in, you need to seek legal advice from your attorney. There are different computer software programs that attorneys use that allow them to enter income numbers in, who will be claiming the children on their tax records and specific parameters to get close to an estimated support numbers. This will give you some range of where the numbers should be for either child or spouse support. But, there is no guarantee that estimated amount will be allocated to you.
Once the numbers are calculated, those numbers are very important to your financial planner, because they take those numbers and plug them into your post-divorce budget to see if those numbers will meet your financial needs. Or if there is a deficit, what kind of income would you need to generate or earn to ensure that you will not go into debt.
Your financial advisor will be able to help you create a budget that will highlight your cashflow standpoint that will help you make decisions pre-and post-divorce.