Are all Duct sizing calculators tedious? The wheel ductulators and computerized versions are good but you still are left entering different combinations given a set of design parameters. HVAC Buddy Duct Calc has unique sliders for inputs so you can quickly find the appropriate velocity, friction, or size. Calculations are based on friction loss equations recommended in the ASHRAE Handbook of Fundamentals 2009. Various sizing capabilities include the ability to choose even or odd sizing for realistic duct sizes as well as an aspect ratio for rectangular ducts. Two modes of operation: Airflow helps you choose duct sizes given a particular airflow, useful for designing a duct run. "Size" mode evaluates the airflow given a size which is useful for evaluating existing installations. Features: • Solve by Airflow or by Duct Size • Size round, rectangular, and oval ducts • Multiple materials galvanized, Flex, etc. • Rounding to Even or Odd Sizes • Constrain by size, airflow, velocity, or friction loss • Equations from ASHRAE Handbook of Fundamentals 2009 • Supports Inch-Pound (IP) or Metric (SI) HVAC Buddy Duct Calc - helps you choose optimal duct sizes for systems in residential, commercial and industrial buildings. HVAC Buddy - HVAC applications for handheld devices on all popular platforms.