Ductwright HVAC Calculator

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About this app

Ductwright is an HVAC and sheet metal calculator for HVAC technicians, installers, sheet metal workers and apprentices. It works like a hardware calculator: a galvanized-grey chassis, real keys and a clear LCD, with each answer labelled so you know what you are reading.

AIRFLOW AND DUCTS
• Airflow = area × velocity, in cfm or L/s, with conversion between them
• Velocity from airflow and duct, or from velocity pressure
• Round duct sizing by equal friction, 0.1 in wg per 100 ft unless you set another rate
• Friction rate for a given airflow and duct
• Rectangular duct: the other side for a round size, and the round equivalent diameter

FANS AND LOADS
• Fan laws: new airflow, static pressure and brake power for a speed change
• Sensible heat from airflow and temperature difference, in BTU/h, tons and kW
• Airflow required for a given load

FITTINGS AND SHEET METAL
• Offset travel and angle
• Radius elbow throat, heel and centreline lengths at any angle
• Round taper flat pattern: slant height, pattern radii and sweep angle
• Bend allowance, bend deduction and outside setback, with K-factor presets for soft aluminium and steel

AIR AND REFRIGERANT
• Dew point and wet bulb from dry bulb and relative humidity
• Saturation temperature from gauge pressure for R410A, R32, R454B, R134A, R290 and R22
• Superheat above dew and subcooling below bubble, with glide shown for blends

WORKS THE WAY YOU DO
• Inches, cfm, ft/min, °F and psig, or millimetres, L/s, m/s, °C and bar
• A results strip shows every solved value at once
• 10 memories, a tape of your calculations, reference tables and a key guide
• Large keys you can hit with gloves on
• Export a job strip: the tape with inputs, stamped and ready to attach to a lift plan, sign-off or take-off, as text or PDF

FREE TO TRY, THEN UNLOCK ONCE
Free to try: every feature for 7 days. Then unlock Pro once — no subscription, no ads, works offline.

PRIVATE BY DESIGN
Works offline, no account, no data collected. Everything stays on your device.

How it's calculated: the formulas and tables behind every result, at https://wrightcalc.app/ductwright/

Questions or feedback: [e-mail]

Results are computed from the formulas shown for each function and are provided for reference only. They do not replace a load calculation, duct design or the equipment maker's data. Verify every result against the code in force and the authority having jurisdiction, and follow safe refrigerant handling practice. The developer accepts no liability for loss or damage arising from use.

What’s new

Bug fixes and improvements.