HVAC & Airflow calculators

Actual to standard cubic feet per minute.

Fan size from the air changes you want.

Compare design CFM against measured CFM per branch.

Compressor size from tool air demand.

Air density from temperature, pressure and altitude.

CADR needed for a room and resulting ACH.

Tank volume for a compressed air system.

Powered attic ventilator size and intake area.

Livestock barn airflow by animal weight.

Exhaust fan size for any bathroom.

Hydrogen dilution airflow for battery banks.

Convert blower door CFM50 to ACH50 and natural ACH.

Combustion air openings for a gas or oil boiler room.

Airflow from heating or cooling load.

Blade span and CFM for a room.

Airflow in cubic feet per minute from room size and air changes.

Airflow per ton of cooling capacity.

Convert CFM to cubic metres per minute.

Convert CFM to litres per second.

Convert cubic feet per minute to cubic metres per hour.

Vent area and fan CFM for a coop.

Stack effect draft from height and temperature.

ACH and HEPA coverage by ISO class.

Pipe diameter for a compressed air line.

Vent area or fan CFM for a crawl space.

Supply and return split with a health verdict.

Vent length allowance and airflow check.

Cross-sectional area of round or rectangular duct.

Pressure drop along a duct run.

Cooling season heat gain into ducts.

CFM25 leakage against code limits.

Total surface area of a duct run.

Air speed in a duct from CFM and duct size.

Workshop dust collector sizing by machine.

Round equivalent of a rectangular or oval duct.

Balanced ventilation airflow for a home.

New CFM, pressure and power from a speed change.

Brake horsepower and running cost of a fan.

Face velocity and pressure loss across an air filter.

Realistic airflow through flexible duct.

Airflow from measured velocity and duct area.

Feet per minute to metres per second.

Outdoor air rate for occupied spaces.

Exhaust CFM from sash opening and face velocity.

Exhaust fan size for a garage or workshop.

Combustion and cooling air for a standby generator room.

Heating load for a greenhouse.

Exhaust fan sizing for a greenhouse.

Inline fan size for a grow tent with filter losses.

Rough air conditioner size for a home.

Moisture load and dehumidifier CFM for an indoor pool.

Moisture removal load from airflow and grain difference.

Replacement air for powerful exhaust fans.

Design friction rate for duct sizing.

Exhaust offset needed to hold a room negative.

Airflow from an orifice plate differential pressure reading.

Case fan CFM for a PC build.

BTU sizing for a portable air conditioner.

Sub-slab depressurisation fan sizing.

Kitchen hood size by cooktop width and type.

Supply register size from CFM and face velocity.

Commercial kitchen hood exhaust airflow.

Return grille size from return CFM.

Net free area for intake and exhaust vents.

Fresh air exchange rate for a sauna room.

Cooling tonnage and airflow for IT load.

Approximate A-weighted sound level from a sone rating.

SFP in W/(L/s) or W/CFM for system efficiency comparison.

Booth airflow from cross-draft face velocity.

Total external static pressure health check.

Evaporative cooler sizing by air changes.

Main trunk duct size from total CFM.

Velocity pressure and equivalent velocity from a pitot reading.

Annual dollar savings from adding a VFD to a fan.

Capture airflow for a welding hood or arm.

Wet bulb from dry bulb and relative humidity.

Fan size and attic vent area for whole-house cooling.

BTU/hr sizing for a wine cellar cooling unit.