HVAC Calc – Duct & Airflow

Tired of complex charts and formulas on the job site?
Air Duct Calc is your all-in-one HVAC toolkit, designed to give you instant answers without an internet connection. Simplify your workflow and get accurate results in seconds.
YOUR FIELD CALCULATIONS, SIMPLIFIED:
▶ Instant Duct Sizing Forget the manual work. Input your airflow and velocity to get precise circular and rectangular duct dimensions instantly.
▶ One-Tap Airflow & Velocity Working with existing ducts? Enter the area to immediately calculate the airflow in both CFM and L/s.
▶ Accurate Friction Loss Based on the Darcy-Weisbach formula, get reliable friction loss data (Pa/m & in.wg/100 ft) to ensure your system is designed correctly.
▶ Essential Conversion Tools
* Rectangular to Circular: Seamlessly find the equivalent hydraulic diameter for any duct.
* SI & Imperial: Switch between metric and imperial units on the fly.
BUILT FOR THE REAL WORLD:
* 100% Offline Functionality: Perfect for basements, new constructions, and areas with no signal.
* PDF Report Generator: Quickly create and share professional PDF reports of your calculations.
* Clean & Fast Interface: No clutter. Just the tools you need, right when you need them.
Whether you're an engineer, a technician, or a student, Air Duct Calc is the essential tool to make your job easier. Download now!

HVAC Calc brings the essential duct & airflow math to your phone—offline and on site.
* Duct Sizing: diameter from Q & V; rectangular area/velocity and equivalent (ASHRAE)
* Airflow: velocity + area → flow (L/s & CFM side-by-side)
* Rect ↔ Circ: equivalent circular & hydraulic diameter (4A/P)
* Friction Loss: Darcy–Weisbach with Swamee–Jain (Pa/m & in.wg/100 ft)
* Psychrometrics: dew point (Magnus)
* PDF Expert: Images → PDF, plus HVAC report generator & viewer
* Units: instant SI/Imperial toggle
* Design: polished dark UI built with SwiftUI