App Overview
DuctLab helps sheet-metal fabricators, HVAC installers, technicians, apprentices, and contractors turn fitting dimensions into calculated measurements, diagrams, material estimates, and ordered fabrication steps. Jobs and calculations stay on the device unless you explicitly share an exported PDF.
Main Features
- Create, duplicate, edit, and delete projects with an optional customer, job number, and notes.
- Add rectangular transitions, square-to-round fittings, duct offsets, and rectangular or round elbow layouts.
- Calculate true lengths, slopes, angles, circumferences, developed perimeters, net sheet area, and fitting-specific layout values.
- Review a diagram, measurement results, cautions, and numbered fabrication steps for each part.
- Set part quantities and seam allowances, or duplicate a part to explore a variation.
- Estimate total sheet area, waste, stock sheets required, and material cost.
- Use Imperial or Metric dimensions and estimate cost in USD, CAD, AUD, EUR, or GBP.
- Reference common rectangular and round duct sizes, galvanized sheet gauges, and typical seam allowances.
- Create a multi-page fabrication PDF and send it to a destination you choose through the iOS share sheet.
Quick Start
Supported Fitting Layouts
- Rectangular Transition: enter top and bottom openings, transition length, and horizontal or vertical offsets to review the centerline true length, four panel slopes, centerline angle, area, and development sequence.
- Square to Round: enter the rectangular opening, round diameter, length, offsets, and pattern divisions to review circumference, division spacing and angle, true lengths, area, and triangulation steps.
- Duct Offset: enter width, height, offset rise, and longitudinal run to calculate true travel, offset angle, travel per unit rise, area, and a four-face development method.
- Elbow Layout: choose rectangular or round, 45° or 90°, a centerline radius, and 1–12 segments to review centerline, throat, and heel arcs, developed perimeter, segment angle, area, and assembly steps.
Material Estimate
DuctLab totals the calculated sheet area of all parts by quantity, includes any seam-allowance area, adds the selected waste percentage, divides the result by the configured stock-sheet area, and rounds the sheet count up to a whole sheet. Estimated cost is the whole-sheet count multiplied by the price per sheet.
This is an area-based estimate, not a nesting optimizer. It does not prove that all developed patterns will fit on the estimated sheets or account for grain, coating direction, stock defects, machine margins, unusable offcuts, coil widths, purchasing minimums, taxes, delivery, or labor.
PDF Export and Sharing
The fabrication package is generated offline on the device. Its project page can include the project name, customer, job number, notes, units, part count, material estimate, and part index. Each part page can include its specification, quantity, seam allowance, diagram, measurements, totals, cautions, and numbered steps.
Tap Export Fabrication PDF, then choose a destination in the iOS share sheet. Before sending, printing, or saving the document, review its contents and confirm the intended file, recipient, printer, storage location, and destination app.
Common Questions
- Why did the material estimate change? Review every part quantity, dimension, seam allowance, waste percentage, stock-sheet size, and price. Each of these values can change the total.
- Why is the sheet count higher than total area divided manually? DuctLab adds the configured waste and rounds the result up to a whole sheet.
- Why does an Imperial value look different after switching units? DuctLab converts stored dimensions when the project's unit system changes. Verify converted values and the display precision before fabrication.
- Why does my shop layout differ? Seam profiles, brake or lock-former setups, radius conventions, segmentation, material thickness, and shop standards vary. Treat the app's references and steps as starting points.
- Will projects sync to another device? DuctLab does not operate a cloud-sync service. Use your Apple-managed device backup settings and export important fabrication packages when you need a portable record.
Accuracy and Shop Safety
DuctLab is a calculation, estimating, and reference aid. It is not a substitute for a full-size shop layout, approved drawings, professional engineering, code review, manufacturer instructions, airflow design, pressure classification, material specifications, or qualified fabrication judgment. Compound transitions may twist, tight square-to-round fittings may need more divisions, and centerline-radius or seam conventions may differ between shops.
Before ordering material, cutting, forming, assembling, or installing, independently verify all dimensions, pattern points, true lengths, angles, quantities, gauges, seams, allowances, clearances, reinforcement, connections, costs, equipment settings, job specifications, and applicable codes. Follow safe tool procedures and use suitable guarding, workholding, ventilation, and personal protective equipment.
Privacy and Data Handling
DuctLab requires no account and performs project storage, geometry calculations, diagrams, estimates, and PDF creation on the device. It does not operate a DuctLab server or proprietary cloud-sync service. See the DuctLab Privacy Policy for details about local storage, Apple services, PDF sharing, retention, deletion, and the full disclaimer.
Support Contact
For help, bug reports, or App Review clarification, contact the developer. Include the DuctLab version, device model, iOS version, unit system, fitting type, and a short description of the issue. For a calculation question, include the relevant dimensions and settings, but remove customer names, job numbers, notes, and other confidential information first.
- Developer: JiaBao Dai
- Email: 298030287@qq.com
- Response time: Usually within 24 business hours
- Terms of Use: Apple Standard End User License Agreement