// Free Engineering Tool

Flow, Velocity & Pipe Size Calculator

Solve the pipe continuity equation Q = V × A for whichever value you need — velocity in a pipe, flow capacity, or the diameter required for a target velocity. Includes typical design-velocity guidance for pumped liquids and air, and a table of velocity across standard pipe sizes. Verified against the standard formula.

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Solve For

Flow Rate

m³/h

Velocity

m/s

Inside Diameter

Continuity: Q = V × A, with A = π·D²/4. Enter inside (bore) diameter, not nominal size. Velocity guidance is general (water/pumped liquid): suction < 2 m/s, discharge 2–3 m/s. Confirm against the specific service and code.

Typical Design Velocities

Pump suction< 2 m/s

Pump discharge2 – 3 m/s

General water1 – 3 m/s

Compressed air15 – 30 m/s

Results

Velocity—

Cross-Section Area—

Flow—

—

Velocity by Pipe Size — Current Flow

ID (mm)	Area (mm²)	Velocity (m/s)	Status

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