Simply enter the values into the fields, choose the shape of ducting and units of measurement and see the results. No matter if you start from airflow values, size A parameter or velocity values, you will get the results immediately. Then you can compare them by choosing different duct shapes to find the best solution for you. For your comfort, calculator is able to calculate both in metric and imperial units.The color of the speed scale signalizes suitability of the calculated velocity. Red means an unacceptable, orange risky and green suitable velocity. Blue signalizes excessively dimensioned.