Pipe flow velocity calculator
Calculate liquid or gas velocity in a pipe from the flow rate, and see the velocity in every pipe size at once to pick the right line size.
Inside diameter—
Velocity—
Velocity—
Velocity in every size
Green rows fall in the common 1–3 m/s range for pumped water. Typical guides: pump suction 0.6–1.5 m/s, discharge 1.5–3 m/s, steam 20–40 m/s.
| NPS | ID (mm) | Velocity (m/s) | Velocity (ft/s) |
|---|
Formula
v = Q / A, where A = π·ID²/4. With Q in m³/h and ID in mm: v (m/s) = Q × 354 / ID². Multiply m/s by 3.281 for ft/s.
Frequently asked questions
What is a good water velocity in a pipe?
For pumped water, 1–3 m/s is common: about 0.6–1.5 m/s on pump suction and 1.5–3 m/s on discharge, to balance pipe cost against pressure drop and erosion.
How do I calculate velocity from flow rate?
Divide the volumetric flow by the internal cross-sectional area: v = Q / (π × ID² / 4). With Q in m³/h and ID in mm, v = Q × 354 / ID² m/s.
How do I convert gpm to m³/h?
Multiply US gpm by 0.2271 to get m³/h.
Last updated 2026-11-02