A simple but useful app for iPhone and iPad to get quick dimensions of a HVAC duct is available in the AppStore. It has been developed by Carmel Software, a widely experienced company that owns other building services apps.
It is a very intuitive app that helps you to obtain quick data of a HVAC duct. There are three different modes to know the characteristics of a duct: “Size by Airflow”, “Size by Dimensions” and “Range of Duct Sizes”. The main differences are the kind of data that you need to enter in the app.
You can get more information about this app in the official AppStore: HVAC Duct Sizer