How accurate are these calculations?

Formulas adhere strictly to industry engineering and trade handbook standards. Always allow safety margins for critical real-world installations.

Does this tool transmit any personal or project data?

No. All calculations run strictly client-side inside your browser. No data ever leaves your computer.

Is my data uploaded anywhere?

No. The calculation runs in your browser with JavaScript — nothing you type is sent to a server or stored.

Does it work on a phone?

Yes. The layout adapts to small screens and needs no app or signup.

HVAC Duct Sizing & Friction Loss Calculator

Size round and rectangular air supply ducts based on airflow CFM, friction loss rate per 100ft, and target air velocity (FPM).

100% free
Private in browser
No signup
No watermarks

Target Airflow (CFM)

Friction Rate (in. w.g. / 100 ft)

Recommended Round Duct Diameter (Inches)

Airflow Velocity (Feet Per Minute - FPM)

748

Duct Cross Sectional Area (sq ft)

1.07

Acoustic Comfort Rating (1: Quiet, 2: Standard, 3: High Velocity)

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About HVAC Duct Sizing & Friction Loss Calculator

Size round and rectangular air supply ducts based on airflow CFM, friction loss rate per 100ft, and target air velocity (FPM). You get Recommended Round Duct Diameter, Airflow Velocity and Duct Cross Sectional Area straight away. Everything runs in your browser, so your data never leaves your device.

How to use HVAC Duct Sizing & Friction Loss Calculator

Enter your specific project and environment input parameters
Review the computed values, conversions, and ratings in real-time
Adjust variables to simulate different scenarios and tolerances

Key features

Instant dynamic client-side calculations
Interactive sliders and numeric inputs
Industrial and engineering formulas validated against standards
100% private and offline in-browser execution

Frequently asked questions

How accurate are these calculations?: Formulas adhere strictly to industry engineering and trade handbook standards. Always allow safety margins for critical real-world installations.
Does this tool transmit any personal or project data?: No. All calculations run strictly client-side inside your browser. No data ever leaves your computer.
What does the HVAC Duct Sizing & Friction Loss Calculator give me?: It works out Recommended Round Duct Diameter, Airflow Velocity and Duct Cross Sectional Area, updating live as you change the inputs.
Is my data uploaded anywhere?: No. The calculation runs in your browser with JavaScript — nothing you type is sent to a server or stored.
Does it work on a phone?: Yes. The layout adapts to small screens and needs no app or signup.

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Engineering formulas for mechanical fluid systems. Calculate pipe hydrostatic burst pressure, thermal expansion loops, orifice plate flow metering, and HVAC CFM duct friction rates.