Rectangular and Round Duct Sizes Chart - A Field Duct Sizing
Rectangular Duct Sizes Chart
| Duct Size(cfm) | 4″ |
|---|---|
| 60 | 6×4 |
| 90 | 8×4 |
| 120 | 10×4 |
| 150 | 12×4 |
| 180 | 14×4 |
| 210 | 16×4 |
| 240 | 18×4 |
| 270 | 20×4 |
| 300 | 22×4 |
| 330 | 24×4 |
| 40 | 21/2×10 |
| 70 | 21/2×14 |
| 150 | 21/2×30 |
| Duct Size(cfm) | 6″ |
| 60 | 4×6 |
| 110 | 6×6 |
| 160 | 8×6 |
| 215 | 10×6 |
| 270 | 12×6 |
| 320 | 14×6 |
| 375 | 16×6 |
| 430 | 18×6 |
| 490 | 20×6 |
| 540 | 22×6 |
| 600 | 24×6 |
| 650 | 26×6 |
| 710 | 28×6 |
| 775 | 30×6 |
| 100 | 31/2×14 |
| 220 | 31/2×30 |
| Duct Size(cfm) | 8″ |
| 90 | 4×8 |
| 160 | 6×8 |
| 230 | 8×8 |
| 310 | 10×8 |
| 400 | 12×8 |
| 490 | 14×8 |
| 580 | 16×8 |
| 670 | 18×8 |
| 750 | 20×8 |
| 840 | 22×8 |
| 930 | 24×8 |
| 1020 | 26×8 |
| 1100 | 28×8 |
| 1200 | 30×8 |
| 1300 | 32×8 |
| 1400 | 34×8 |
| 1500 | 36×8 |
| Duct Size(cfm) | 10″ |
| 120 | 4×10 |
| 215 | 6×10 |
| 310 | 8×10 |
| 430 | 10×10 |
| 550 | 12×10 |
| 670 | 14×10 |
| 800 | 16×10 |
| 930 | 18×10 |
| 1060 | 20×10 |
| 1200 | 22×10 |
| 1320 | 24×10 |
| 1430 | 26×10 |
| 1550 | 28×10 |
| 1670 | 30×10 |
| 1800 | 32×10 |
| 1930 | 34×10 |
| 2060 | 36×10 |
| 2200 | 38×10 |
| 2350 | 40×10 |
| Duct Size(cfm) | 12″ |
| 150 | 4×12 |
| 270 | 6×12 |
| 400 | 8×12 |
| 550 | 10×12 |
| 680 | 12×12 |
| 800 | 14×12 |
| 950 | 16×12 |
| 1100 | 18×12 |
| 1250 | 20×12 |
| 1400 | 22×12 |
| 1600 | 24×12 |
| 1750 | 26×12 |
| 1950 | 28×12 |
| 2150 | 30×12 |
| 2300 | 32×12 |
| 2450 | 34×12 |
| 2600 | 36×12 |
| 2750 | 38×12 |
| 2900 | 40×12 |
| 3050 | 42×12 |
Round Duct Sizes Chart
| Flexible Duct | |
|---|---|
| Duct Size | Design Airflow |
| 5″ | 50 |
| 6″ | 75 |
| 7″ | 110 |
| 8″ | 160 |
| 9″ | 225 |
| 10″ | 300 |
| 12″ | 480 |
| 14″ | 700 |
| 16″ | 1000 |
| 18″ | 1300 |
| 20″ | 1700 |
| Round Metal Pipe | |
|---|---|
| Duct Size | Design Airflow |
| 5″ | 50 |
| 6″ | 85 |
| 7″ | 125 |
| 8″ | 180 |
| 9″ | 240 |
| 10″ | 325 |
| 12″ | 525 |
| 14″ | 750 |
| 16″ | 1200 |
| 18″ | 1500 |
| 20″ | 2000 |
See Also