Flow Rate Calculator (Continuity)
Q = A·V — volumetric flow from pipe diameter and velocity, in L/s, m³/h and US gpm.
Continuity: for incompressible flow the product A·V is constant along a pipe, so halving the area doubles the velocity.
Formula
Flow Rate Calculator (Continuity) is a free flow rate calculator for process, mechanical and water engineers — instant, accurate and 100% client-side, with the governing formula and reference shown next to the result so the number can be defended, not just quoted.
About Flow Rate Calculator (Continuity)
Q = A·V — volumetric flow from pipe diameter and velocity, in L/s, m³/h and US gpm. The calculation implements Q = A·V = (π·D²/4)·V (Çengel & Cimbala, Fluid Mechanics, §5-2 (conservation of mass)). Continuity: for incompressible flow the product A·V is constant along a pipe, so halving the area doubles the velocity.
How to use Flow Rate Calculator (Continuity)
- 1Enter Pipe inner diameter in mm.
- 2Enter Average velocity in m/s.
- 3Read Flow rate, Flow rate, Flow area instantly — no submit button needed.
- 4Need US units? Flip the SI/Imperial toggle and every field converts.
Why use Flow Rate Calculator (Continuity)?
- ✓Implements the standard formula — Q = A·V = (π·D²/4)·V
- ✓Reference cited on-page: Çengel & Cimbala, Fluid Mechanics, §5-2 (conservation of mass)
- ✓One-click SI ⇄ Imperial toggle — values convert in place, physics stays in SI
- ✓Live worked example: the substitution recomputes from your numbers
- ✓Runs entirely in your browser — nothing uploaded, free forever
Frequently asked questions
What formula does the Flow Rate Calculator (Continuity) use?+
It computes Q = A·V = (π·D²/4)·V, per Çengel & Cimbala, Fluid Mechanics, §5-2 (conservation of mass). The formula is displayed under the result along with a worked example substituted with your own inputs.
What should I keep in mind when using this calculator?+
Continuity: for incompressible flow the product A·V is constant along a pipe, so halving the area doubles the velocity.
Does this work for any fluid?+
Yes — density and viscosity are inputs (with common fluids suggested in the field hints), so the same physics applies to water, oils, gases and process fluids. Compute always runs in SI internally, so unit mix-ups can't corrupt the result.
Is the Flow Rate Calculator (Continuity) free to use?+
Yes — completely free, no sign-up, no limits. It runs client-side in your browser, so inputs stay private and results are instant even on slow connections.
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