Convert US gallons to kilograms for water, milk, oil, honey, gasoline, and custom densities. Bidirectional with pounds, liters, fluid ounces, and liquid weight comparison table.
Converting between gallons and kilograms requires knowing the density of the liquid, because gallons measure volume while kilograms measure mass. A gallon of water weighs about 3.785 kg, but a gallon of honey weighs about 5.374 kg, and a gallon of gasoline only about 2.858 kg. The density of the liquid determines the weight.
This converter lets you select from common liquids (water, milk, vegetable oil, honey, gasoline, ethanol) or enter a custom density. It handles both directions — gallons to kilograms and kilograms to gallons — and also shows the result in liters, pounds, grams, and fluid ounces. A comparison table shows the weight of one gallon for each liquid at a glance.
Whether you are calculating the weight of a water tank, determining fuel load for a vehicle, weighing cooking ingredients by volume, or shipping liquids internationally, this tool accounts for density differences that simple volume-to-weight converters miss.
Unlike volume-only converters, this tool accounts for liquid density when converting gallons and kilograms. Users can select common liquids or enter a custom density value to get accurate mass and volume results for planning loads, recipes, shipping calculations, safety checks, inventory planning, and repeatable operational decisions in real workflows with clearer documentation and fewer conversion mistakes during handoffs.
Kilograms = Gallons × 3.78541 L/gal × density (kg/L) Gallons = Kilograms ÷ (3.78541 × density) For water (density = 1.0 kg/L): 1 US gallon = 3.785 kg = 8.345 lbs
Result: 3.785 kg (8.345 lbs)
1 US gallon = 3.78541 liters. With water density of 1.0 kg/L: 3.78541 L × 1.0 = 3.785 kg, which is 8.345 pounds.
Volume (gallons, liters) measures space occupied. Mass (kilograms, pounds) measures the amount of matter. The link between them is density: mass = volume × density. This is why a gallon of a dense liquid like honey (1.42 kg/L) weighs much more than a gallon of a light liquid like gasoline (0.755 kg/L).
Fuel calculations for vehicles, aircraft, and boats require converting fuel volume to weight. Shipping costs for liquids depend on both volume and weight (dimensional vs actual weight). Cooking recipes sometimes specify liquid ingredients by weight for precision.
The US gallon (3.785 L) and the UK imperial gallon (4.546 L) are different units with the same name. The imperial gallon is about 20% larger. Always verify which gallon system is being used, especially for fuel economy comparisons (mpg US vs mpg UK).
One US gallon of water weighs approximately 3.785 kilograms or 8.345 pounds at room temperature.
Gallons measure volume, not weight. Different liquids have different densities, so the same volume weighs differently. A gallon of honey weighs 42% more than a gallon of water.
This converter uses US gallons (3.78541 liters). UK (imperial) gallons are larger at 4.54609 liters.
Density is listed on safety data sheets (SDS) for industrial liquids. For food items, search for "[liquid name] density kg/L." Common values: water 1.0, milk 1.03, olive oil 0.92.
Yes — the converter shows pounds alongside kilograms. For water: 1 gallon ≈ 8.345 lbs.
Yes. Density changes with temperature. Water at 4°C is 1.000 kg/L, at 25°C is 0.997 kg/L, at 100°C is 0.958 kg/L. For most purposes, using 1.0 is sufficient.