Free · Volume to weight converters

Gallons to Pound-Mass by Substance Density

Find the mass of a measured fluid volume using a substance preset or your own density, with US, imperial and dry gallon choices.

  • Formula & worked example
  • Private in your browser
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Calculator inputs

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How to use this calculator

  1. Enter the known values in the units shown. Results update as you type.
  2. Where results are editable, change one to solve backwards. Lock a value to hold it fixed.
  3. Use the worked example to check the method. Reset restores the starting fields.

Private by default

Inputs and results stay in this browser tab. Bookify does not upload or store the values you enter.

Formula and method

For a custom density of 1,000 kg/m³, 0.45359237 US liquid gallons have mass 3.785411784 lb. A gallon’s mass depends on the material and its conditions.

Mass = density × volume; 1 US liquid gallon = 0.003785411784 m³; 1 lb = 0.45359237 kg

Worked example

Enter these known values and leave the other values blank.

Substance preset or custom density
Custom substance
Density at the intended conditions
1000 kg/m³
Volume and gallon definition
0.45359237 US gal
Mass in avoirdupois pounds
3.7854 lb

Assumptions and limitations

  • Density, volume and mass are positive. The result is pound-mass, not pound-force.
  • Substance presets are illustrative fixed densities. Temperature, formulation and pressure affect the actual density; use Custom for measured data.
  • US liquid, imperial and US dry gallons are different volume units. Select the gallon definition used by the original measurement.

Common questions

Is there one pounds-per-gallon conversion?

No. A volume unit does not specify mass. Multiply the volume by the density of the material at the relevant conditions.

Does the calculator include the container?

No. It gives the contents’ mass. Add the empty container’s mass separately if you need gross mass.

References

The US dry gallon uses one eighth of a 2150.42-cubic-inch bushel, replacing the rounded captured volume factor. Bookify replaces the captured rounded US gallon with the exact 3.785411784-liter definition. Bookify uses exact customary mass and volume definitions for density units, replacing rounded factors in the reference. Prices per thousand US gallons use the same exact gallon as the volume inputs.

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