Flow Velocity Factors
Volume Flow (Q)
cu nanometres (nm³) cu micrometres (µm³) cu thous (thou³) cu millimetres (mm³) cu centimetres (cc, cm³) millilitres (mL) teaspoons (tsp, usa) teaspoons (tsp, metric) tablespoons (Tbsp, usa) tablespoons (Tbsp, metric) cu inches (in³) fluid ounces (fl oz, imp) fluid ounces (fl oz, usa) cups (usa) cups (metric) pints (pt, usa liq) pints (pt, imp) litres (L) gallons (gal, usa liq) gallons (gal, imp) cu feet (ft³) barrels (bbl, oil) cu yards (yd³) cu metres (m³) kilolitres (kL) megalitres (ML) cu kilometres (km³) cu miles (mi³) cu nautical miles (nmi³)
per (/)
nanosecond (ns) microsecond (µs) millisecond (ms) second (s) minute (min) hour (hr) day (d) week (wk) month (mo) year (yr)
Diameter (ø)
Select diameter unit nanometres (nm) micrometres (µm) thousands of an inch (thou) millimetres (mm) centimetres (cm) inches (in) feet (ft) yards (yd) metres (m) kilometres (km) miles (mi) nautical miles (nmi)
Calculate Speed of Flow
Flow Velocity (v)
nanometres (nm) micrometres (µm) thousands of an inch (thou) millimetres (mm) centimetres (cm) inches (in) feet (ft) yards (yd) metres (m) kilometres (km) miles (mi) nautical miles (nmi)
per (/)
nanosecond (ns) microsecond (µs) millisecond (ms) second (s) minute (min) hour (hr) day (d) week (wk) month (mo) year (yr)

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User Guide

This tool will calculate the flow velocity in any units from the specified volumetric flow rate of a substance flowing through a round duct or pipe of a chosen diameter. For each new calculation a unique conversion scale will be generated for the range of volumetric flow rates and flow speeds for the diameter specified.

Formula

The flow velocity formula used by this calculator is:

v = Q / (π · (ø / 2)²)

Derived from:

v = Q / A

A = π · r²

r = ø / 2

Symbols

• Q = Volume flow rate
• v = Flow velocity
• A = Cross-sectional area
• r = Radius
• ø = Diameter

n.b. This formula assumes uniform flow conditions within the entire cross-sectional area of pipe, without any friction losses near to surfaces.

Volumetric Flow Rate Measured

Enter the volumetric amount of substance that will flow pass in a unit of time.

Diameter

Enter the inside diameter of the circular pipe or duct.

Flow Velocity Calculation

This is the speed at which the substance is moving.