Pipe Size Estimator

Formula

D = 2·√(Q / (π·v)) where Q = flow (m³/s) and v = target velocity (m/s).

Variables

• Q — flow rate (m³/h, converted to m³/s)
• v — target mean velocity (m/s)
• D — required internal diameter (m)

Example

85 m³/h at 1.5 m/s: Q = 0.0236 m³/s; D = 2·√(0.0236/(π·1.5)) = 0.142 m ≈ 142 mm.

Application

Useful for preliminary pipe sizing in water and industrial service.

Limitations

This is a mean-velocity estimate. Standard pipe sizes, friction, fittings and fluid properties must be considered. Full hydraulic design requires a qualified engineer.