General Engineering Calculators
Universal unit converter and everyday conversions — free for everyone.
Unit Converter
FreeFree engineering unit converter for HVAC: pressure, temperature, airflow, BTU/h, kW, tons, energy, torque, R-value, microns and more — metric and imperial.
BTU/h ↔ kW ↔ Tons
FreeConvert BTU/h to kW, tons of refrigeration, watts and horsepower instantly. Free HVAC capacity converter with formulas and examples.
CFM ↔ L/s ↔ m³/h
FreeConvert CFM to litres per second and cubic metres per hour. Free airflow unit converter for HVAC ventilation and duct design.
R-Value ↔ RSI
FreeConvert imperial R-value to metric RSI and U-factor. Free insulation converter used for Canadian and US building codes.