There are normal peak flow values that are based upon age, gender, height, and race. Since there is such a wide range in these normal values with some people naturally on the higher end and other people naturally on the lower end, it is best to determine your personal best peak flow. Please read our peak flow monitoring information at http://www.nationaljewish.org/disease-info/diseases/asthma/living/tools/peak/index.aspx to learn more.
For adult women I think around 400 to 500 is good. I have at tiems been able to do 600. Ask your doctor.