HVAC Tools Library
Browser-based calculators and reference tools for air balancing and HVAC work. All calculations happen in your browser — no data is sent anywhere, no account required.
📝 Educational use
Available Calculators
Air Changes per Hour (ACH) Calculator
Enter supply airflow (CFM) and room dimensions to calculate ACH. Compare results against ASHRAE reference values for common space types.
Open calculator →CFM Variance Calculator
Enter design and measured CFM to calculate the difference and variance percentage. Commonly referenced tolerance is ±10%, but requirements vary by project specifications and TAB standard.
Open calculator →Planned Tools
These tools are in development. Cards are listed here for reference — no separate pages yet.
CFM Calculator
Calculate supply airflow requirements from room area, occupancy, or ventilation rate.
Duct Velocity Calculator
Convert between CFM, duct area, and face velocity. Useful for rough duct sizing checks.
Air Balance Report Reader
Guide to interpreting the columns, tolerances, and notation in a standard TAB report.
Static Pressure Explainer
Interactive walkthrough of total static pressure, external static pressure, and what affects them.
Room Airflow Estimator
Estimate required supply airflow from cooling load and temperature differential.
About these tools
ABS calculators are provided for educational purposes and general estimation. Results should be verified against project specifications, applicable mechanical codes, and the judgment of qualified engineers and TAB professionals. Tolerance requirements and acceptance criteria vary by project, contract, and applicable standard.