Online Duct Size Calculator – Free HVAC Duct Sizer Tool (2025 Updated)

Designing a proper HVAC duct system is one of the most important steps in achieving balanced airflow, reduced noise, and overall system efficiency. To make this process easier for technicians, draftsmen, and MEP engineers, we have created a free online duct size calculator that works instantly for round ducts.

👉 Try the tool here:

Online Duct Size Calculator

Whether you are working on designing new ductwork or checking existing CFM requirements, this tool gives you accurate results within seconds—without installing any software.

What Is the Duct Size Calculator?

The Online Duct Size Calculator is a simple web-based tool that helps you determine the correct
round duct diameter, based on:

• Required CFM (Cubic Feet per Minute)
• Desired air velocity
• Basic friction and sizing principles used commonly in the HVAC industry

Instead of manually checking charts or using old mobile apps, your results appear instantly on the screen.
It’s fast, accurate, and made especially for MEP professionals in the Gulf region.

Why Use Our Duct Sizer?

Here’s what makes this tool stand out:

Fast & Instant Results

Simply enter the airflow (CFM) and the calculator gives you an optimized duct size in seconds.

No Software Installation

Everything runs directly in your browser. You can use it on desktop, laptop, or mobile—no setup required.

Based on Standard HVAC Guidelines

The calculator follows commonly accepted air velocity ranges for supply, return, and exhaust ducts, suitable for most commercial and residential projects.

Beginner Friendly

The interface is simple and clean. It is perfect for draftsmen, junior engineers, and students who need quick and reliable results while learning HVAC design.

Designed for Gulf MEP Standards

The tool is built keeping in mind the airflow practices used in UAE, KSA, Qatar, Kuwait, Oman, and other Gulf countries, so it fits naturally with your daily design work.

Where This Tool Helps You

You can use the duct sizer calculator in many practical situations, such as:

• Preparing HVAC shop drawings
• Routing ducts in AutoCAD or BIM models
• Checking and verifying CFM values
• Site work, inspections, and quick checks
• Design calculations during project coordination
• Training new team members and students

Having a quick browser-based calculator saves time and reduces manual mistakes, especially when you are working under tight deadlines.

How to Use the Duct Size Calculator

Using this online tool is very simple:

1. Open the calculator in your browser.
2. Enter the airflow (CFM) you require for the duct section.
3. Select or adjust the air velocity if needed.
4. View the recommended duct diameter shown instantly on the screen.
5. Use this value directly in your drawings and calculations.

No PDFs, no charts, no complicated tables to read. Just input and result.

👉 Open the tool now:

Online Duct Size Calculator (Round Duct)

Who Should Use This Tool?

This online duct sizer is useful for:

• HVAC draftsmen and CAD operators
• MEP design engineers
• Site engineers and supervisors
• BIM modelers working on duct layouts
• Students and fresh graduates learning HVAC design

If you regularly work with duct sizing, checking airflow, or preparing HVAC shop drawings, this tool can quickly become part of your daily workflow.

Future MEP Tools on MEPBase

We are continuously working on more practical tools for the MEP community. In the future, we plan to add:

• Advanced duct sizer with more options
• ESP (External Static Pressure) calculator
• Pump head and pipe sizing calculators
• Chilled water flow and velocity tools
• BTU and cooling load quick calculators

All tools will be browser-based so you can access them anytime without installing anything.

Try the Duct Sizer Tool Now

You can start using the duct size calculator right now. It’s completely free and does not require any login or registration.

👉 Click below to open the tool:

Use the Online Duct Size Calculator

If you have any feedback or suggestions for improving the tool, feel free to contact us through the MEPBase website. Your input will help us build even better tools for the MEP community.