Duct Size Calculator
Size a round or rectangular air duct from airflow and target air velocity, with equivalent required cross-sectional area.
Required duct area
0.0556 m²
Round duct diameter
266 mm
Rectangular duct
333 × 167 mm
Formula and design note
Area A = Q / v after converting m³/h to m³/s; round diameter D = √(4A/π). The rectangular result has the exact same area at the selected aspect ratio. Final duct design must also check friction loss, fitting losses, noise, available static pressure, leakage, diffuser throw and balancing; equal-area rectangles are not automatically equal-friction equivalents to round ducts.