Is a peak flow meter reading of around 320 normal for a 20 year old 4 11 female? i got a at home peak flow meter because i feel like i have shortness of breath at times, not sure if its stress related. would exercising 1hr prior affect reading?

A 20 year old with 60 inch height has a predicted peak expiratory flow of 372 liters/minute. Please reference these website for more information https://www.lung.org/lung-health-diseases/lung-disease-lookup/asthma/living-with-asthma/managing-asthma/measuring-your-peak-flow-rate & https://www.asthma.com/understanding-asthma/severe-asthma/asthma-control-test/

Continue to monitor the best of three readings at the same time of day prior to exertion. The pattern of a decreased value should be related to factors such as illness, symptoms of wheezing and cough. The one value itself may not be accurate, but could be improved. A virtual consultation with Healthtap is available to review your Peak flow log.

I don't think peak flow monitoring will have any value in your case. It monitors ability to forcefully expel air from your lungs. We use it to monitor asthmatic patients who have expiratory wheezing problems. I would add that sensation of shortness of breath while at rest but not with exertion is characteristic of tension and stress. If this pertains to you, consider stress management therapy.