A flow meter reports volume per time. Enter its US gallons per minute reading, the liquid’s density in pounds per US gallon, and the transfer duration to calculate mass flow and total transferred mass.

Formula: lb/min = US gal/min × lb/US gal; lb/hour = lb/min × 60; transferred US gal = average US gal/min × minutes; transferred lb = US gal × lb/US gal

Worked example

At 12 US gal/min and an entered density of 8 lb/US gal, mass flow is 96 lb/min or 5,760 lb/hour. A 15-minute transfer moves 180 US gal with a mass of 1,440 lb.

Match the gallon definition

Both volume inputs use US liquid gallons. Imperial gallons and US dry gallons are different units. This tool assumes the meter reports actual liquid volume at the conditions represented by the density, rather than a differently corrected reference volume.

Use density for the actual liquid

Density connects the flow reading to mass. Use a value appropriate to the liquid’s composition and temperature. The example’s 8 lb/US gal is an arithmetic input, not a claim about a particular liquid.

Totals assume the entered average stays representative

If flow varies, enter the time-weighted average over the stated duration. Density is assumed constant throughout. The calculator does not derive flow from pressure, predict pump performance, or include container tare weight. Zero flow or zero runtime is allowed.

Explore the related calculation

For a different starting point, try the liquid shipment weight calculator or return to the main calculator. Browse the complete tool directory for this site.

Reference and corrections

The definitions and assumptions above follow these sources; the examples and calculator arithmetic are original to this page.

Found a problem? Email contact@gallonstopounds.org.

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