Duct Mate: HVAC Duct Sizer

Flat oval, return air sizing, and room-by-room CFM planning — all in one buy-once app. Compare up to 18 duct sizes. Export CSV & PDF. No subscription ever.

Duct Mate is the HVAC duct sizing tool built for the field — fast, offline, and transparent. Size ducts by CFM, analyze existing runs, find equivalent sizes, and calculate design friction rate from static pressure — all without creating an account or connecting to the internet.

CORE TOOLS — ALL IN ONE APP

▸ Duct Size by Airflow Enter CFM, choose supply/return/exhaust, pick a shape and material, tap "Size" — get a recommended duct size instantly. Switch between friction and velocity methods. Supports round, rectangular, flex, and flat oval ducts with galvanized metal, flex duct, and duct board materials.

▸ Existing Duct Analyzer Got a duct that's already installed? Enter its size to find out how much CFM it can actually handle (Capacity Solver mode), or check what velocity and friction you're getting at a given airflow (Diagnostic mode). This is the reverse-sizing feature field techs have been asking for.

▸ Equivalent Duct Calculator Convert round to rectangular, rectangular to round, round to flat oval — every equivalent size shows cross-sectional area, equivalent diameter, and velocity change. Perfect for material swaps and retrofit work.

▸ Friction Rate Helper Calculate design friction rate the Manual D way: enter external static pressure, subtract component pressure losses (coil, filter, registers, grilles), divide by total equivalent length (supply + return). Built-in TEL calculator: simply tap a straight duct run, select fittings (14 types in the library), add equivalent length — no manual lookup tables needed. One tap to apply your friction rate back to the duct sizer.

DESIGNED FOR THE FIELD

• Works completely offline — no internet, no account needed • US (IP) and SI (metric) units with one-tap switching • Keyboard input, no cumbersome sliders • Quick-pick buttons for common CFM values and friction rates • Every result shows the formula, assumptions, and warnings • Save jobs, pin favorites, share results as text

PRO FEATURES — ONE-TIME PURCHASE

Unlock everything with a single purchase. No subscriptions.

FREE —————————————— PRO ($4.99, one-time) Round, rectangular, flex ——— + Flat oval Return Air Helper ————————— + Return Air recommendations Room Split Calculator ———— + Room CFM planning 3 candidate sizes —————————— 18 candidate sizes 3 saved calculations ——————— Unlimited saves Text sharing ———————————————— + CSV & PDF export Standard settings —————————— + Advanced settings Friction Rate Helper —————— + Fitting Equivalent Length library

TRANSPARENT, NOT A BLACK BOX

Duct Mate is not a replacement for ACCA Manual D, but it's built to support Manual D workflows. Every calculation displays: • The underlying formula and assumptions • Standard air density (0.075 lb/ft³) • Material roughness and friction factor • Velocity limits with warnings when exceeded • Aspect ratio cautions for rectangular ducts • A clear disclaimer for professional verification

TRUSTED BY HVAC PROS

No subscription. No account. No data collection. Works offline wherever the job takes you.

Download Duct Mate today — the duct sizer that works the way you do.