Pipe Flow Velocity Calculator
Calculate average fluid velocity from volumetric flow and inside diameter.
Steady incompressible liquid series systems with user pump curves. This standalone quick calculator remains available below.
PRELIMINARY RESULT
- Average velocity
- 0.99 m/s
Calculation detail
Formula: v = Q / A
Volumetric flow is converted to m³/s and divided by the circular internal pipe area.
Internal diameter sensitivity
For fixed volumetric flow, velocity varies with 1/D². A 10% smaller bore raises average velocity by 23.46%.
At 72.00 mm bore, average velocity would be 1.228 m/s. This comparison does not establish an acceptable pipe size.
Technical verification
Equation checked: 2026-09-15 · Units checked: 2026-09-15 · Independent numerical case: Pass
Source basis: TEXTBOOK — OpenStax University Physics, 14.5 Fluid Dynamics
Unit basis: m³/h ÷3600 → m³/s; mm ÷1000 → m
Independent example: 18 m³/h = 0.005 m³/s, D=80 mm: A=0.00502655 m²; v=0.994718 m/s.
Scope: Completely filled circular pipe and average velocity only. No pressure drop, Reynolds number, friction, fittings, compressibility, cavitation or pipe-size acceptability check.
Technical verification is not professional engineering certification and does not approve a specific real-world design.