# Air Duct Calculator

## Flexible Duct Friction Loss Calculator

1. Enter Friction Loss Per 100' of duct (inches of water), Duct Airflow (CFM), Duct Length and the number of bends.

2. Read Duct Diameter (inches) and Duct Velocity (FPM).

1. Enter Round Duct Diameter (inches), Duct Airflow (CFM), Duct Length and the number of bends.

2. Read Friction Loss Per 100' of duct (inches of water) and Duct Velocity (FPM).

## Sheet Metal Duct Friction Loss Calculator

1. Enter Duct Airflow (CFM), Duct Velocity (FPM), Duct Length and the number of bends.

2. Read Round Duct Diameter (inches) and Friction Loss Per 100' of duct (inches of water).

1. Enter Friction Loss Per 100' of duct (inches of water), Duct Airflow (CFM), Duct Length and the number of bends.

2. Read Duct Diameter (inches) and Duct Velocity (FPM).

1. Enter Round Duct Diameter (inches), Duct Airflow (CFM), Duct Length and the number of bends.

2. Read Friction Loss Per 100' of duct (inches of water) and Duct Velocity (FPM).

## Equivalent Rectangular Duct

1. Enter Round Duct Diameter.

2. Enter the Desired Length of the Rectangular Duct.

## Equivalent Round Duct Diameter

1. Enter the Length of the Rectangular Duct.

2. Enter the Width of the Rectangular Duct.