Omni CFM Calculator vs DuctPro

Easily calculate CFM and ACH, and find the right filters for your negative air machines. Built for contractors, healthcare construction pros, and clean air specialists. Features: -CFM Calculator -ACH Calculator -Filter Finder by size and machine compatibility

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. —