HVAC Calculators puts a field-ready reference in your pocket. Browse 40 purpose-built tools for system design, airflow, refrigeration, diagnostics, and economics so you can check loads, balance air, and verify performance before you leave the rooftop.
**What you can do**
Size comfort systems with BTU Load, AC/Furnace/Boiler/Heat Pump, ventilation load, make-up air, humidity control, and expansion valve calculators, plus an optional Manual J-lite per-surface envelope mode for defensible heating and cooling loads.
Dial in airflow with Duct Sizing (round or rectangular, 1:1 through 4:1 aspect ratios), CFM vs ACH, friction loss, fan law, grille/diffuser sizing, and static pressure tools.
Keep refrigeration and hydronics on point with refrigerant charge, line sizing, coil performance, pump head, water/gas pipe sizing, and glycol concentration helpers.
Troubleshoot faster using superheat & subcooling, temp rise/drop, dew point, wet bulb, relative humidity, moist air enthalpy, compressor efficiency, and an ASHRAE 62.1 ventilation workflow.
Run the numbers behind the job with unit conversions, wire size and Ohm’s Law, motor amperage, energy cost estimates, efficiency payback, ROI, and life-cycle cost comparisons.
**Built for the field**
Real-time answers update as you type, with optional formula callouts when you need to explain the math.
Smart search plus categorized sections so you can jump straight to the right calculator.
On-device calculations mean you can keep working even when the mechanical room has no signal.
Unit preferences (°F/°C, in. w.c./Pa/kPa) persist across sessions so every calculator opens the way you expect.
Help and abbreviation references keep apprentices productive and remind veterans of rarely used constants.
Light and dark mode support for easy reading in any environment.
Core calculators are free forever. An optional one-time Pro upgrade unlocks the full suite of 40 tools.
Whether you’re sizing a replacement rooftop, double-checking duct velocities, or building a payback story for an upgrade, HVAC Calculators gets you from rule-of-thumb to defensible numbers in seconds.
Disclaimer: These tools provide quick estimates for educational and planning purposes. Always confirm final selections with manufacturer data, engineering references, and all applicable codes and standards before installation.
Show more
