Pipe Flow Rate and Velocity Calculator
Convert volumetric flow and average speed in a full circular pipe. Calculate mass flow and the time to fill an entered volume.
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Result
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Calculation steps
Work through one step at a time or reveal the complete calculation. The steps use your current inputs.
How to calculate
Use the internal circular cross-section area, then apply flow=area×average velocity. Multiply volumetric flow by density for mass flow and divide target volume by flow for fill time.
A=πd²/4; Q=Av; mass rate=ρQ; fill time=V/Q
Worked example
A 100 mm diameter pipe carrying 60 L/min has average velocity about 0.127324 m/s. Filling 1000 L at this constant flow takes 16.6667 minutes.
Assumptions and input details
Assume a full circular pipe, constant density and steady flow. Diameter is 1e−9–1e6 m; flow or speed and volume are nonnegative; density is positive. Zero flow has no finite filling time for a positive volume. Velocity is cross-sectional average, not centre-line speed. US liquid and Imperial gallons are distinct. This continuity calculation does not determine pressure loss, pump performance, viscosity or safe pipe size.
References: OpenStax flow and average velocity
Unit definitions
Unit selection is independent of language. Each selector contains only units for its physical quantity. Calculations use defined base units internally.
Choose from 23 length definitions, including explicitly labelled regional measures. Area conversions square the length factor; geometric volumes cube it.
The 36 volume definitions distinguish US liquid, US dry and Imperial measures. Cups carry an explicit definition. Japanese shō is 2401/1331 L and a gō is one tenth of it; the explicitly labelled 180 mL rice cup is separate.
Regional measures are not interchangeable merely because their names look similar. This is a documented selection, not a claim to include every historical unit.
NIST measurement tables · UK Imperial definitions · Japanese traditional units · Mainland China and Hong Kong unit distinctions
Using this calculator
Can I enter my own problem?
Yes. Replace the example values with your own inputs. The result, calculation steps, tables and applicable diagrams update from those inputs. Blank or invalid values clear the result; example values are never silently substituted for missing inputs.
Are the results exact?
Results use floating-point arithmetic and displayed rounding. Read the formula, assumptions and any stated data precision before interpreting the result.
Is my input uploaded?
The calculation runs in your browser. No account, file upload or external AI service is required. Inputs are not saved between page reloads.
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