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# Ducts - Cross-Sectional Area vs. Diameter

### Circular ventilation ducts and cross-sectional areas - Imperial Units

Ducts - Cross-Sectional Area vs. Diameter - Imperial Units
Duct Diameter Area
(in)(mm)(ft2)(m2)
8 203 0.3491 0.032
10 254 0.5454 0.051
12 305 0.7854 0.073
14 356 1.069 0.099
16 406 1.396 0.130
18 457 1.767 0.164
20 508 2.182 0.203
22 559 2.640 0.245
24 609 3.142 0.292
26 660 3.687 0.342
28 711 4.276 0.397
30 762 4.900 0.455
32 813 5.585 0.519
34 864 6.305 0.586
36 914 7.069 0.657

### Circular ventilation ducts and cross-sectional areas - Metric Units

Ducts - Cross-Sectional Area vs. Diameter - SI Units
Duct DiameterArea
(mm)(m2)(mm2)(in2)
63 0.003 3019 4.7
80 0.005 4902 7.6
100 0.008 7698 11.9
125 0.012 12076 18.7
160 0.020 19856 30.8
200 0.031 31103 48.2
250 0.049 48695 75.5
315 0.077 77437 120
400 0.125 125036 194
500 0.196 195565 303
630 0.311 310736 482
800 0.501 501399 777
1000 0.784 783828 1215
1250 1.225 1225222 1899

## Related Topics

### • Ventilation

Systems for ventilation and air handling - air change rates, ducts and pressure drops, charts and diagrams and more.

## Related Documents

### Circular Ducts - Dimensions

Standard size of circular ventilation air ducts.

### Duct Velocity

Calculate velocities in circular and rectangular ducts - imperial and SI-units - online calculator.

### Ducts Sizing - the Velocity Reduction Method

The velocity reduction method can be used when sizing air ducts.

### Equivalent Diameter - Rectangular vs. Circular HVAC Ducts

Rectangular equivalent diameter for air flows between 100 - 50000 cfm.

### Fluid Flow - Equivalent Diameter

Convert rectangular and oval duct geometry to a equivalent circular diameter - online calculator with imperial and SI-units.

### Fluid Flow - Hydraulic Diameter

Calculate hydraulic diameter for pipes and ducts.

### Rectangular Ducts - Dimensions

Commonly used metric dimensions for rectangular air ducts in ventilation systems.

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