Rectangular Duct Exterior Coating Quantity calculator.
Measure four exterior duct faces and only the supplied exposed end faces, then deduct known uncoated area.
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.
Area = Σ(2(width + height) × length + exposed end count × width × height − uncoated area) × count. Does not select fire-resistant coatings, duct specification or corrosion protection.
A worked example
Illustrative inputs only. Product properties and design dimensions are not recommendations for your project.
- Supplied coat count
- 1
- Chosen product coverage
- 1 m²/L
- Selected container volume
- 1 L
- Measured exterior width
- 0.3 m
- Measured exterior height
- 0.2 m
- Measured coated length
- 2 m
- Supplied exposed end faces
- 0
- Measured uncoated area per piece
- 0 m²
- Identical pieces
- 1
Selected coating containers: 2 containers
Specified exterior surfaces only. Coating suitability and coat count are not selected.
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 fire-resistant coatings, duct specification or corrosion protection.
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.