# How do I convert gallons to kg?

Converts gallons to kilograms and back for water, milk, flour, sugar, and other ingredients, from what each one weighs per liter.

- Page: https://www.acalculator.org/convert/gallons-to-kg
- JSON spec: https://www.acalculator.org/convert/gallons-to-kg.json
- Version: 54ec0a726ae6

## Default answer

Example with the default inputs (Gallons (gal) 1, Ingredient Water at 4 °C, 0.999975 kg per L): 1 gal = 3.785317 kg (Water at 4 °C, 0.999975 kg per L).

## Inputs

| Key | Label | Description |
| --- | --- | --- |
| value | Gallons (gal) | The amount in gallons to convert. |
| result | Kilograms (kg) | The same amount in kilograms. |
| ingredient | Ingredient | What you are measuring. A cup of flour weighs less than a cup of water. |

## Outputs

| Key | Label | Description |
| --- | --- | --- |
| value | Gallons (gal) | The amount in gallons to convert. |
| result | Kilograms (kg) | The amount in kilograms. |

## Method

kg = gallons × 3.785411784 × 0.999975, where kilograms per liter depends on the ingredient (water at 4 °C: 0.999975 kg)

## Assumptions

- Grams per cup are USDA FoodData Central (SR Legacy) portion weights for one level US cup (8 US fluid ounces): all-purpose flour 125 g (FDC 168894), granulated sugar 200 g (FDC 169655), brown sugar, packed 220 g (FDC 168833), powdered sugar, unsifted 120 g (FDC 169656), whole milk 244 g (FDC 171265), butter 227 g (FDC 173410), olive oil 216 g (FDC 171413), honey 339 g (FDC 169640), white rice, uncooked 185 g (FDC 169756).
- Water is pure water: 0.999975 kg per liter at 4 °C and 0.998207 kg per liter at 20 °C, from the Tanaka et al. (2001) density formula.
- Other ingredients use their USDA cup weight: kilograms per liter = grams per cup ÷ 236.5882365.
- The answer shows at most 6 decimal places; the calculation keeps full precision.

## Worked examples

1. value = 1, ingredient = water gives result = 3.785317. Source: Density of pure water from Tanaka et al. (2001), Metrologia 38, 301: 999.9749 kg/m³ at 4 °C, 998.2067 kg/m³ at 20 °C, as 0.999975 kg per liter.
2. value = 1, ingredient = milk gives result = 3.904. Source: USDA FoodData Central SR Legacy 171265: 1 cup = 244 g.

## FAQ

### How many kilograms are in a gallon?

It depends on the ingredient, because a volume does not fix the weight. 1 gal is about, in kilograms: all-purpose flour 2; granulated sugar 3.2; brown sugar, packed 3.52; powdered sugar, unsifted 1.92; water at 4 °C 3.785; water at 20 °C 3.779; whole milk 3.904; butter 3.632; olive oil 3.456; honey 5.424; white rice, uncooked 2.96.

### How do I convert gallons to kg?

kg = gallons × 3.785411784 × 0.999975, where kilograms per liter depends on the ingredient (water at 4 °C: 0.999975 kg). For example, 1 gal of water at 4 °C is 3.785317 kg.

### Does a liter of water weigh 1 kg?

Almost. Pure water weighs 0.999975 kg per liter at 4 °C, where it is densest, and 0.998207 kg per liter at 20 °C (Tanaka et al. 2001). Other liquids differ more: a liter of whole milk weighs about 1.03 kg and a liter of olive oil about 0.91 kg (USDA).

## Sources

- USDA FoodData Central, SR Legacy portion weights for 1 cup: FDC 168894 all-purpose flour 125 g; FDC 169655 granulated sugar 200 g; FDC 168833 brown sugar, packed 220 g; FDC 169656 powdered sugar, unsifted 120 g; FDC 171265 whole milk 244 g; FDC 173410 butter 227 g; FDC 171413 olive oil 216 g; FDC 169640 honey 339 g; FDC 169756 white rice, uncooked 185 g. https://fdc.nal.usda.gov/
- Tanaka, M. et al. (2001), Recommended table for the density of water between 0 °C and 40 °C based on recent experimental reports, Metrologia 38, 301–309: pure water 999.9749 kg/m³ at 4 °C and 998.2067 kg/m³ at 20 °C. https://doi.org/10.1088/0026-1394/38/4/3
- NIST SP 811 (2008), Guide for the Use of the International System of Units, Appendix B.8. https://www.nist.gov/pml/special-publication-811