Duct Calculator Elite
HVAC Ductulator & Duct Sizing
$9.99 · Designed for iPad. Not verified for macOS.
Duct Calculator Elite™ replaces your ductulator wheel with fast, precise duct sizing built on the friction-loss equations of the ASHRAE Handbook — Fundamentals. Trusted by HVAC professionals, mechanical engineers, and contractors since 2013. One price — no subscriptions, no ads, no accounts.
THREE CALCULATORS, ONE TAP APART
• DUCT SIZE BY AIRFLOW — Set airflow and either velocity or friction, and solve for round and rectangular duct dimensions. Specify the rectangular aspect ratio to match your available space. The nearest standard round and rectangular sizes are shown with the friction they actually run at.
• DUCT SIZE BY DIMENSION — Enter a round diameter or rectangular height and width, then lock airflow, velocity, or friction and solve for the remaining variables.
• PRESSURE DROP — Convert between duct length, pressure drop, and friction. Find the exact pressure drop of a given installation, or the maximum duct length that maintains your design pressure drop.
DESIGN TOOLS
• FRICTION RATE — Enter your available static pressure and duct run, add fittings from a built-in list of typical equivalent lengths (elbows, tees, wyes, supply boots), and get your total effective length and target friction rate — the Manual D style residential design workflow. Then send the result straight into Duct Size by Airflow with one tap.
• AIRFLOW FROM HEAT LOAD — Enter a sensible heat load and temperature difference to get the required airflow, corrected for air density.
ENGINEERING-GRADE MATH
Solves the Colebrook friction-factor equation directly for each duct material's surface roughness — the same method behind the ASHRAE friction chart — rather than interpolating from lookup tables. Roughness values come from Table 1 of the 2025 ASHRAE Handbook — Fundamentals, and the app shows you the one it used. Rectangular results use the Huebscher equivalent-diameter equation; air density is corrected for your temperature and elevation, and air viscosity for your temperature, so results hold up at altitude and outside room temperature. Below the turbulent range where the published methods agree, results are flagged as approximate.
PRECISE ENTRY, BUILT FOR THE FIELD
Type exact values directly in place — no cumbersome sliders, no pop-up entry screens. Confirm with a tap and every dependent value recalculates instantly. A clean layout keeps every result in view as you work, and everything runs fully offline.
CONFIGURED FOR REAL JOB CONDITIONS
• Duct dimensions: inches, centimeters, or millimeters
• Airflow: CFM, cubic feet per second, cubic meters per second, cubic meters per hour, or liters per second
• Velocity: feet per second, feet per minute, or meters per second
• Pressure loss: inches of water per 100 ft or pascals per meter
• Duct materials: galvanized steel, spiral steel, galvanized spiral (corrugated), aluminum, uncoated carbon steel, PVC plastic pipe, concrete, phenolic duct (pre-insulated), flexible duct (metallic), flexible duct (helix core, insulated), fibrous glass liner (spray coated), and fibrous glass liner (faced, smooth)
• Air temperature (°F, °C, K) and elevation (feet or meters) corrections
The next time you head to a meeting or out to the job site, leave the ductulator at home — everything you need is on your iPhone or iPad.
Questions or ideas for the next version? Email techsupport@cyberprodigy.com — we read every message.
Added three more duct materials to the list, plus airflow in m³/h and the ASHRAE roughness value behind every material. The air temperature and elevation adjustment covers viscosity as well as density.
NEW
• Three more duct materials: phenolic (pre-insulated), galvanized spiral (corrugated), and flexible duct with an insulated helix core. The two fibrous glass liners now use ASHRAE's names.
• Airflow in cubic meters per hour (m³/h).
• Preferences shows the absolute roughness used for every material, from Table 1 of the 2025 ASHRAE Handbook — Fundamentals. Tap ⓘ where ASHRAE gives a range rather than a single number.
• A flag on results where flow leaves the turbulent range and the published friction methods stop agreeing.
NON-STANDARD AIR
Sizing has always adjusted for your air temperature and elevation; this version lets air viscosity vary with your temperature too, as the ASHRAE Handbook prescribes for air outside the chart's range. Near sea level at ordinary temperatures nothing changes; higher or hotter, rates read 3–13% higher than in previous versions, the top of that range only where extreme heat and altitude combine. Your saved air temperature and elevation carry over unchanged; new installs now default the air temperature to 70 °F and the elevation to sea level.
FIXED
• A unit switch now re-checks the converted value against the new unit's range.
• Pressure Drop accepts metric duct length up to 150 m.
The developer, Cyberprodigy LLC, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Collected
The developer does not collect any data from this app.
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- Cyberprodigy LLC
- Size
- 14 MB
- Category
- Utilities
- Compatibility
Requires iOS 15.6 or later.
- iPhone
Requires iOS 15.6 or later. - iPad
Requires iPadOS 15.6 or later. - iPod touch
Requires iOS 15.6 or later. - Mac
Requires macOS 12.5 or later and a Mac with Apple M1 chip or later.
- iPhone
- Languages
English and 7 more
- English, French, German, Japanese, Korean, Portuguese, Simplified Chinese, Spanish
- Age Rating
4+
- 4+
- Copyright
- © Cyberprodigy LLC
