Volumetric Flow Rate Calculator

Volumetric flow rate is how much fluid passes a point in a given time, which is the cross-sectional area multiplied by the average velocity through it. Enter a round bore, a rectangular duct or an area you already have, together with a velocity, and the answer comes back in cubic metres per second, litres per second, gallons per minute and cubic feet per minute at the same time. A second tab takes a volume and the time it took instead, and a third turns any flow into a mass flow once you give it a density. Area times velocity wants the average velocity across the whole section, so a probe reading taken at the centre of a pipe will overstate it.

Calculator Type

Those Dimensions Measured In

Area Measured In

Velocity Measured In

The bore or the duct, and how fast the fluid is moving through it. Enter the inside dimensions, not the outside ones.

Cross Section

Inside Diameter (round)

Inside Width (rectangular)

Inside Height (rectangular)

Cross-Sectional Area (only for the third option)

Velocity (fps) *

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Flow Measured In

Density Given As

Kilograms per cubic metre Pounds per cubic foot Specific gravity (water = 1)

A volumetric flow only becomes a mass flow once you say what the fluid weighs. Gases especially: the density moves with pressure and temperature, so a cubic foot per minute is not a fixed amount of anything.

Volumetric Flow Rate (m3s) *

Density of the Fluid (kgm3) *

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