Duct Weight & Surface Area Calculator
Rectangular
Round / Spiral
26 Gauge (0.906 lb/sqft)
24 Gauge (1.156 lb/sqft)
22 Gauge (1.406 lb/sqft)
20 Gauge (1.656 lb/sqft)
18 Gauge (2.156 lb/sqft)
16 Gauge (2.656 lb/sqft)
Calculation Results
Total Surface Area: 0 sq. ft.
Estimated Weight: 0 lbs
*Includes ~15% allowance for seams and scrap.
How to Calculate Duct Weight
Calculating the weight of HVAC ductwork is essential for determining hanger sizes, support requirements, and material costs. The weight depends on the surface area of the metal and the thickness (gauge) of the sheet metal used.
The Formulas Used
To find the weight, we first calculate the surface area in square feet and then multiply it by the weight factor of the specific gauge.
- Rectangular Duct Area: 2 × (Width + Height) × Length / 12
- Round Duct Area: π × Diameter × Length / 12
- Total Weight: Surface Area × Gauge Factor (lb/sq ft)
Galvanized Steel Gauge Chart
| Gauge | Thickness (inches) | Weight (lb/sq ft) |
|---|---|---|
| 26 | 0.0217 | 0.906 |
| 24 | 0.0276 | 1.156 |
| 22 | 0.0336 | 1.406 |
| 20 | 0.0396 | 1.656 |
| 18 | 0.0516 | 2.156 |
Example Calculation
Suppose you have a 24″ x 12″ rectangular duct that is 10 feet long, made of 24 gauge steel.
- Perimeter: (24 + 12) × 2 = 72 inches.
- Surface Area: (72 / 12) × 10 = 60 square feet.
- Base Weight: 60 × 1.156 = 69.36 lbs.
- Total (inc. seams): Approximately 79.7 lbs.