HVAC Calculator: BTU & AC Load

New: faster Ductulator and updated BTU load tables. Size any AC, furnace, or duct run in seconds — metric & imperial units. Download free and try it on your next job.

Size any system in seconds. HVAC Calculator gives technicians, installers, and DIY homeowners fast, accurate BTU and load numbers — no spreadsheets, no guesswork.

Whether you're sizing an air conditioner, balancing a duct run, or checking a refrigerant charge, every tool you need lives in one app.

WHAT YOU CAN CALCULATE • BTU & Cooling Load — find the right AC size for any room by square footage, climate, and sun exposure • Heating Load — size furnaces and radiators with confidence • Ductulator — duct sizing by friction rate, velocity, and CFM • Tonnage Converter — instant BTU ⇄ ton conversions • Refrigerant Charge — superheat and subcooling checks • Room & Area — square footage and volume in metric or imperial

BUILT FOR THE FIELD • Works offline — no signal needed on the job site • Metric and imperial units • Clean, fast interface designed for gloved hands • Save and share your results • Formulas based on current HVAC industry standards

TRUSTED BY HVAC PROS From apprentices studying for the EPA 608 to seasoned installers, HVAC Calculator replaces bulky charts and slide rules with one tool in your pocket.

Download HVAC Calculator free and size your next job right the first time.