DuctPro

DuctPro is the professional HVAC duct sizing calculator built for field technicians and MEP engineers. Get engineering-grade results in seconds — offline, no subscription.

RESULTS IN 3 TAPS
Enter airflow, select duct type, get the size. Round, rectangular, flat oval, and flexible ducts. Size by friction rate or air velocity. A color-coded performance badge tells you instantly if your duct is optimal, too fast, too slow, or at risk.

ENGINEERING-GRADE ENGINE
Calculations use the Darcy-Weisbach friction equation with Colebrook-White solver — the industry-standard method for duct design. Nine material types with published roughness values: galvanized steel (spiral & rectangular), flexible duct (metallic & non-metallic), fiberglass duct board, fibrous glass liner, PVC, aluminum, and concrete.

FITTINGS & PRESSURE DROP
Calculate total system pressure drop including straight run and all fittings. Ten fitting types with industry-standard loss coefficients: 90° and 45° elbows (round and rectangular), mitered elbow, tee branch and straight-through, concentric reduction, enlargement, and butterfly damper.

PRO MODE
Unlock full 2D lookup tables for rectangular elbows and concentric reductions, plus A/B ratio selector for flat oval ducts. Bilinear interpolation for accurate results at any H/W or area-ratio geometry.

ORGANIZE YOUR WORK
Save calculations with a custom name and notes. Group them into color-coded projects. Export individual calculations as text or PDF, and full projects as CSV. Search your entire history in one tap.

IMPERIAL & METRIC
Switch between I-P and SI units at any time. All inputs and outputs update instantly across every screen.
I-P: CFM · in · ft/min · inWC/100ft
SI: L/s · mm · m/s · Pa/m

6 LANGUAGES
English · Français · Español · Português · Deutsch · Italiano

— 100% offline. No account. No subscription. —