ROUND DUCT SIZE ESTIMATE Round Metal Pipe ... Flex duct = .05" on most metal duct calculator Round metal pipe = .06" on most metal duct calculators

TEL is the Total Effective Length of the longest supply run and the longest return run.

To figure out exactly how big ducts you need for central air conditioning systems, we have prepared complete CFM duct charts for all different kinds of ducts: Duct sizing chart for flex ducts (round ducts …

The following duct sizes are based on a fraction drop of .10 inches per 100 feet of lineal duct. This "Equal-Friction" method of duct sizing should be adequate for normal residential furnace heating and …

Jun 3, 2025 · This flex duct size and CFM chart covers all common sizes at two friction rates. The numbers are those you would obtain using a duct calculator, aka a ductulator.

Oct 7, 2025 · Master CFM duct sizing with our comprehensive guide. Learn to calculate duct sizes, read charts, and apply industry standards for optimal HVAC airflow. Includes step-by-step examples.

Calculate duct size by CFM instantly. Free ductulator for round & rectangular ductwork with velocity, friction loss, and return air sizing. No signup needed.

Calculate optimal duct dimensions for HVAC systems instantly. Input airflow (CFM or L/s) and either velocity (FPM) or friction loss to get recommended round, rectangular, and flat oval duct sizes. …

This article introduces a user-friendly Duct CFM Calculator that allows you to calculate airflow based on duct shape, size, and air velocity. Designed to support both round and rectangular ducts, this tool …

This free, easy-to-use ductulator helps you quickly calculate duct velocity and pressure drop based on design airflow — no charts, no guesswork, and no physical duct wheel required.