DuctPro

Open the Calculator tab. Enter your airflow (CFM or L/s), select the duct type and material, then choose a sizing method — Friction or Velocity. The result updates instantly as you type.

Tap the result card to see the full range of compatible sizes, or tap + Fittings to add pressure drop from elbows, tees, and other fittings.

Friction sizes the duct to hit a target friction rate (e.g. 0.08 inWC/100ft). This is the standard method for most duct systems.

Velocity sizes the duct to hit a target air velocity (e.g. 800 ft/min). Use this when noise or code velocity limits are the driving constraint.

Once you have a result, tap the + Fittings button at the bottom of the result card. In the Fittings sheet, enter a duct run length and add as many fittings as needed. The total ΔP (straight run + fittings) is shown automatically.

Go to Settings → Unit System and toggle between I-P and SI. All screens update instantly — including any result currently on screen.

Pro Mode unlocks more precise fitting calculations using full 2D coefficient tables. It adds:

· H/W ratio input for rectangular elbows (bilinear interpolation)
· Area-ratio lookup for concentric reductions
· A/B ratio selector for flat oval ducts (2, 3, 4, or 6)

Enable it in Settings → Pro Mode.

Tap Save on any result to store it in History. You can give it a name and add notes up to 1,000 characters.

Create Projects (second tab) to group related calculations by job site or system. Assign any saved calculation to a project from its detail view.

Three export options are available:

· Text — share a formatted summary of any single calculation
· PDF — generate a printable calculation sheet
· CSV — export all calculations in a project as a spreadsheet (from Project Detail)

You can also export a quick summary directly from the Calculator result card before saving.

Yes — DuctPro is 100% offline. All calculations run on-device and all data is stored locally. No internet connection is ever required.

Swipe left on any individual entry in History or Projects to delete it.

To clear everything at once, go to Settings → Data → Clear All History or Clear All Projects. Both actions require confirmation.

DuctPro supports English, Français, Español, Português, Deutsch, and Italiano. The app follows your device language automatically, but you can override it at any time in Settings → Language.