There is no formula for setting spousal support / alimony. The court can make its own ruling based upon the financial facts and needs presented to the court.
This is an area where you will need to work closely with your attorney. You have to make certain that all the facts that will help you are properly presented to the court. If there are significant differences between you and your spouse regarding income, employment history, and ability to work we highly suggest you hire a lawyer to assist in determining the need for spousal support.