Facility Toolbox
Estimate, inspect, and equip
These are field estimates for planning and troubleshooting. They are not engineering calculations, equipment-sizing decisions, or code-compliance determinations.
HVAC tons ↔ BTU/hr
Convert nominal cooling capacity between tons and BTU per hour.
How it works: One ton of refrigeration equals 12,000 BTU per hour. Tons × 12,000 = BTU/hr.
Convert
Enter every value to calculate.
Nameplate capacity only. Load calculations and equipment sizing require a design professional.
Fahrenheit ↔ Celsius
Convert temperatures and temperature readings in the field.
How it works: °C = (°F − 32) × 5/9 and °F = (°C × 9/5) + 32.
Convert
Enter every value to calculate.
Square footage and room volume
Floor area and volume for paint, airflow, and material estimates.
How it works: Area = length × width. Volume = area × ceiling height.
Units
Enter every value to calculate.
Paint quantity estimate
Gallons needed for a wall area with adjustable coverage and coats.
How it works: Gallons = (area × coats) ÷ coverage per gallon. Openings are subtracted first.
Enter every value to calculate.
In Building Wrench Pro
Air changes per hour (ACH)
Estimate how many times per hour supply air replaces the room volume.
ACH = (CFM × 60) ÷ room volume in cubic feet.
Filter-change date
Next change date from the last change and your interval.
Next change = last change date + interval in days.
Watts, volts, amps
Solve the basic power relationship for a single-phase load.
Watts = volts × amps × power factor. For resistive loads the power factor is 1.0; motors are lower.