You can see a chart for both adults and children and determine approximately what your maximum peak flow should be. Alternatively, you can go to other sites and enter your age, height, gender and race and have your peak flow calculated.
A more important number is your personal best peak flow. Because your personal best peak flow may vary significantly from your predicted peak flow based on height, age, and gender, your personal best peak flow is very important when you talk to a doctor on the phone or need to go to the emergency department.
American Lung Association. What Is a Normal Peak Flow Rate?