How many pounds is one gallon of water

1 US gallon of water equals 8.35 ( ~ 8 1/4) pounds

Volume to 'Weight' Converter - Chemistry

How to convert 1 US gallon of water to pounds

To convert a quantity of a substance or material expressed as a volume to mass we simply use the formula:

mass = density × volume

We want to calculate the mass in pounds from a volume in US gallons. We have the density table at the bottom of this web page that shows us the densities values in kg/m³, so we will use the folowing formula (see why below):

mass = d × v × vcfmcf, where mcf is the conversion factor to convert from pound to kilogram (table near the end of this page) and vcf is the conversion factor to convert from US gallon to cubic meters.

So, plugging these values in the formula above, we get:

mass = 1000 × 1 × 0.003785410.453592

mass = 3.785410.453592

mass = 8.3454 pounds (answer)

There are other ways to convert from volume to mass. This is one of them.

How to convert from volume to mass (incorrectly called weight)?

Well, by definition of density we just need to use the formula:

mass = density × volume

Example: How much does 2 cubic meters of gasoline weigh in kilograms if the gasoline density is 750 kg/m³?

Plugging the values in the formula, we get

mass = density × volume = 750 × 2 = 1500 Kg

Very simple isn't it? Yes, it is as simple as that. But this works fine when the density value we have (from a chart for example) is defined using the same unit of volume and mass that we will use in the formula. For example, mass in kg and volume in liters. If we have, for example, mass in pounds and volume in gallons, we should do something to correct our result.

To transform the mass from pounds to kilograms we should multiply the mass in pounds by 0.45359237. We will call 0.45359237 the mass conversion factor - mcf

Matematically we write:

mass in kilograms = mass in pounds × mcf or

mkg = mlb × mcf (1)

To transform the volume from gallons to cubic meters we should multiply the volume in cubic meters by 0.003785411784. We will call 0.003785411784 the volume conversion factor - vcf

Matematically we write:

volume in cubic meters = volume in gallons × vcf or

vm³ = vgal × vcf (2)

Now, dividing the equation (1) by the equation (2), we get

mkgvm³ = mlb × mcfvgal × vcf, or

mkgvm³ = mlbvgal × mcfvcf, but mkgvm³ is, by definition, the density (d) in kg/m³, so

d = mlbvgal × mcfvcf

Rearranging the formula above we get

mlb = d × vgal × vcfmcf

Finally, we can generalize this formula any units of mass and volume, since we know how to find the values for mcf and vcf (Check the factor tables below).

m = d × v × vcfmcf

That is exactly the formula that we use in this calculator. You can see how this formula works reading the example above or/and choosing another one at the bottom of this page.

US gallons of water to pounds Chart

Note: some values may be rounded.

These tables contain the most frequently used vcf and mcf.

References:

1. Mass, Weight, Density or Specific Gravity of Liquids
2. Mass, Weight, Density or Specific Gravity of Water at Various Temperatures
3. Full Weight Converter

FAQs on water weight to volume conversion

1 US gallon of water equals how many pounds?

1 US gallon of water is equivalent 8.35 ( ~ 8 1/4) pounds.

How much is 8.35 pounds of water in US gallons?

8.35 pounds of water equals 1 US gallon.

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How much does 1 US gallon of water weigh?

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