Piping
Pipe Velocity / Flow / Diameter Calculator
Flow through a circular pipe relates velocity, volumetric flow rate, and pipe cross-sectional area. Given any two of velocity, flow, and internal diameter, this calculator solves for the third using the continuity equation for incompressible flow.
TypeInteractive calculator — separate from unit conversions
Calculator
Result
Velocity0.63662 m/s
Formulas
Cross-sectional area
A = πD² / 4
Velocity from flow
v = Q / A
Flow from velocity
Q = v × A
Diameter from flow and velocity
D = √(4Q / (πv))
Diagram
Worked example
Water flows at 0.005 m³/s through a pipe with internal diameter 100 mm. What is the velocity?
- 01Convert diameter: 100 mm = 0.1 m
- 02A = π × 0.1² / 4 = 0.007854 m²
- 03v = Q / A = 0.005 / 0.007854
- 04v ≈ 0.6366 m/s
Result
The average pipe velocity is approximately 0.637 m/s.
FAQ
Does this include pipe schedule lookup?
No. You must enter the actual internal diameter. Pipe schedule lookup is not implemented.
Does this calculate pressure drop?
No. Pressure drop calculation requires friction factor, pipe length, and fittings data, which are outside the scope of this calculator.
Does this calculate Reynolds number?
No. Reynolds number calculation is deferred to a future release.
Is this velocity the centreline velocity?
No. This is the average (bulk) velocity across the pipe cross-section, which is what is used for most engineering calculations.