Calculator
Duct Weight Calculator
Estimate the weight of ductwork for material orders, freight, and hanger sizing. Enter round or rectangular dimensions, gauge, and material to get surface area, bare-metal weight, and total pounds with a fabrication allowance. Free, no signup.
Free
20 × 8" · 26 ga galvanized · 25 linear ft
Total sheet-metal weight
122 lb
106 lb bare + 15% allowance · 4.86 lb/ft
Surface area
116.7 ft²4.667 ft²/ft · 56.0" perimeter
Bare metal weight
106 lb0.906 lb/ft² at 26 ga galvanized
Waste / seam allowance
16 lb15% for seams, laps, hangers, scrap
Total weight
122 lb4.86 lb per linear ft
Sheet weight reference (lb/ft²)
| Gauge | Galvanized | Aluminum | Stainless |
|---|---|---|---|
| 26 ga | 0.906 | 0.224 | 0.780 |
| 24 ga | 1.156 | 0.284 | 1.040 |
| 22 ga | 1.406 | 0.357 | 1.300 |
| 20 ga | 1.656 | 0.452 | 1.560 |
| 18 ga | 2.156 | 0.569 | 2.080 |
| 16 ga | 2.656 | 0.717 | 2.600 |
Galvanized = MSG steel + zinc coating; aluminum and stainless by material density. Bare-metal weight before the fabrication allowance.
What you'll get
Enter duct size
Choose round or rectangular and enter the diameter or width × height, the length per section, and how many sections.
Pick gauge and material
Select the sheet gauge (26–16) and material — galvanized steel, aluminum, or stainless. Weights follow standard gauge charts.
Get the total weight
See surface area, bare-metal weight, waste allowance, and total pounds, plus an optional material-cost estimate.
How it works
- 1
Enter duct size
Choose round or rectangular and enter the diameter or width × height, the length per section, and how many sections.
- 2
Pick gauge and material
Select the sheet gauge (26–16) and material — galvanized steel, aluminum, or stainless. Weights follow standard gauge charts.
- 3
Get the total weight
See surface area, bare-metal weight, waste allowance, and total pounds, plus an optional material-cost estimate.
Why sheet-metal contractors calculate duct weight
Duct weight drives real decisions: how much sheet metal to order, whether a load fits on the truck, and how to size and space hangers so runs are supported to SMACNA standards. Bare-metal weight is surface area × the sheet weight per square foot for the gauge and material — for example, 26-gauge galvanized weighs 0.906 lb/ft² (Manufacturers’ Standard Gauge steel plus zinc coating).
Surface area comes straight from the geometry: rectangular duct is 2 × (width + height) ÷ 12 × length in feet; round is π × diameter ÷ 12 × length. This calculator adds a 15–20% allowance for seams, laps, flanges, cleats, and scrap, and supports galvanized, aluminum (about one-third the weight), and stainless steel.
Related tools
More free resources to help you price jobs, stay organized, and capture leads.
Business Templates
Free invoices, estimates, and work orders for your trade.
Browse templatesAI Receptionist
Let Larry answer every call while you focus on the job.
Learn moreContractor Blog
Guides on pricing, hiring, marketing, and operations.
Read guidesHVAC Licensing
State licensing requirements, exams, and renewal rules for hvac contractors.
View statesDuct Weight Calculator FAQs
How do you calculate the weight of ductwork?
Multiply the duct’s surface area by the sheet weight per square foot for its gauge and material. Rectangular surface area = 2 × (width + height) ÷ 12 × length (ft); round = π × diameter ÷ 12 × length. Add a 15–20% allowance for seams, laps, and scrap to get fabricated weight.
How much does galvanized duct weigh per square foot?
By Manufacturers’ Standard Gauge (including zinc coating): 26 ga ≈ 0.906 lb/ft², 24 ga ≈ 1.156, 22 ga ≈ 1.406, 20 ga ≈ 1.656, 18 ga ≈ 2.156, and 16 ga ≈ 2.656 lb/ft². Aluminum is roughly one-third the weight of steel at equal thickness.
What gauge should HVAC duct be?
SMACNA selects minimum gauge from the largest duct dimension and pressure class. At low pressure (½ in.wg), rectangular duct up to 24" typically uses 26 ga, 25–48" uses 24 ga, and 49–60" uses 22 ga. Round duct can go lighter than rectangular at the same size due to spiral-seam rigidity.
Is this duct weight calculator free?
Yes. Every tool on CloseCrew is free for HVAC and sheet-metal contractors — no account required.
