HVAC Calculators
5 free professional-grade tools. HVAC load and sizing calculators for technicians
Heating & Cooling
BTU Calculator
Calculate the heating and cooling BTU requirements for a room based on square footage, insulation, climate zone, windows, and occupancy.
HVAC Load Calculator
Perform a simplified Manual J HVAC load calculation for residential buildings. Estimates heating and cooling loads based on building size, construction quality, climate zone, and occupancy.
AC Tonnage Calculator
Calculate the correct AC tonnage for your home based on square footage, climate zone, insulation quality, and other factors. 1 ton = 12,000 BTU/h.
Ductwork & Airflow
Duct Size Calculator
Calculate the required duct size for your HVAC system based on airflow (CFM), duct shape, and maximum velocity per ASHRAE guidelines.
Airflow CFM Calculator
Calculate the required airflow in CFM for any room based on volume and air changes per hour (ACH), or per ASHRAE 62.1 ventilation standards.