All HVAC Calculators
20+ professional calculators for HVAC technicians and contractors. ASHRAE based.
Load Calculations
Calculate heating and cooling loads for residential and commercial buildings
Residential Load Calculator
Quick BTU calculation for homes using Manual J simplified method. Climate zones, insulation, windows.
Commercial Load Calculator
Block load calculation for commercial spaces with occupancy, lighting, and equipment factors.
Heat Loss/Gain Calculator
Detailed envelope heat transfer through walls, windows, roof, floor, and infiltration.
Ductwork & Airflow
Size ducts and calculate airflow requirements
Duct Sizing Calculator
Size supply and return ducts using equal friction or velocity method. Round and rectangular.
CFM Calculator
Calculate required CFM based on tonnage, room size, ACH, or sensible heat load.
Air Velocity Calculator
Calculate velocity from CFM and duct size, or solve for CFM or duct area.
Ventilation Rate (ASHRAE)
Calculate outdoor air requirements per ASHRAE 62.1 and 62.2 standards.
Fan Laws Calculator
Calculate fan performance changes using affinity laws for speed, flow, pressure, and power.
Blower Door Test
Interpret blower door results, calculate ACH50, and compare to energy code requirements.
Room Pressurization
Calculate airflow for pressure control in clean rooms, hospitals, and laboratories.
Refrigeration & Charging
Refrigerant calculations and system diagnostics
Refrigerant Charge Calculator
Calculate charge for R-410A, R-22, R-32. Account for line set length and vertical lift.
Superheat Calculator
Calculate superheat and target values for fixed orifice systems. Charging guidance.
Subcooling Calculator
Calculate subcooling and verify proper charge for TXV systems.
PT Chart / Saturation
Pressure-temperature lookup for R-410A, R-22, R-32, R-134a, R-404A, R-407C.
Psychrometrics
Air property calculations and comfort analysis
Equipment Sizing
Size equipment and utility connections
Reference
Quick reference guides and data tables