Centred Rectangular Duct Transition Sheet Area calculator.
Measure the four trapezoidal faces of an already specified centred rectangular transition, excluding seam and flange stock.
Your inputs
Use measurements from your plan and properties from your chosen product. Any prefilled values are illustrative.
A clear estimate starts here.
Enter your dimensions and product details to see the quantity and purchase breakdown.
Formula and assumptions
How this calculation works.
Face area = (width1 + width2) × hypot(length, (height1 − height2)/2) + (height1 + height2) × hypot(length, (width1 − width2)/2). Does not select transitions, airflow, pressure loss, sheet gauge or an unfoldable cutting layout.
A worked example
Illustrative inputs only. Product properties and design dimensions are not recommendations for your project.
- Usable area per selected sheet
- 2 m²
- First end width
- 0.4 m
- First end height
- 0.2 m
- Second end width
- 0.4 m
- Second end height
- 0.2 m
- Supplied axial length
- 1 m
- Identical transitions
- 2
Area-only sheet lower bound: 2 sheets
Area lower bound only; complete trapezoid blank fit, seams, flanges and fabrication waste are excluded. Not a purchase-ready cutting plan.
Before you purchase
Use dimensions from your plan and properties from your chosen product. Any design spacing, section or fixing pattern must already be specified.
Does not select transitions, airflow, pressure loss, sheet gauge or an unfoldable cutting layout.
All dimensions, properties and application patterns are user-supplied. No building-code default is inserted.
Method: dimensional arithmetic and user-supplied specifications. Software checks: 2026-10-06. Calculation and review policy.