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Pipe velocity calculator

Calculate fluid velocity from volume flow rate and actual pipe internal diameter.

Enter the project values

All values remain in your browser. Review the assumptions before using the result.

Do not enter nominal pipe size unless it equals the actual bore.
Your result will appear here.Calculate to see the outputs, formula and substituted working.

How the calculation works

Continuity relationship using actual internal bore.

Formula

v = Q ÷ A; A = πD² ÷ 4

Worked example

Flow2 L/s
Internal diameter50 mm
Expected velocity1.019 m/s

Assumptions and limitations

Assumptions

  • The entered diameter is the actual internal diameter.
  • The fluid is treated as incompressible.

What this does not check

  • Does not calculate pressure loss, Reynolds number, noise or erosion.
  • Does not select pipe material or nominal size.
Formula version: 1.0 · Last reviewed: 16 August 2026

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Engineering basis: first-principles calculation using user-entered project data. The calculator does not choose design criteria or replace the complete project-specific engineering design.
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