Gallons to Kg Converter
Convert US gallons to kilograms. Gallons measure volume and kilograms measure weight, so pick a substance — water, whole milk, vegetable oil, flour, sugar, honey, or butter — enter gallons, and get kilograms, pounds, and liters.
Example: with US gallons 5 · Substance Water (1.00 kg/L) → Kilograms: 18.93 kg.
- In pounds41.73 lb
- Volume in liters18.93 L
Computed by the calculator below using its default values. Change any input to see your own numbers.
kg = gallons × 3.785411784 × density (kg/L). One gallon of water is about 3.79 kg; a gallon of milk closer to 3.9 kg.
A gallon's weight depends on what is in it
A US gallon is a fixed 3.785411784 liters of space; its weight is that volume times the density of whatever fills it. Water at roughly 1 kg/L makes a gallon about 3.79 kg (8.35 lb) — the anchor number behind water-jug workouts and aquarium math. Milk is slightly denser at 1.03, so the familiar gallon jug runs near 3.9 kg.
Multiply out bigger jobs the same way: a 5-gallon water jug is 18.93 kg (41.7 lb), which is why office coolers feel like a gym exercise. Light substances flip the intuition — a gallon of flour weighs just 2 kg, while a gallon of honey is a dense 5.38 kg. Density, not the container, does the deciding.
How it’s calculated
Liters = gallons × 3.785411784 (exact NIST US gallon); kg = liters × density (kg/L); pounds = kg ÷ 0.45359237 (exact). Densities used: water 1.00, whole milk 1.03, vegetable oil 0.92, all-purpose flour 0.53, granulated sugar 0.85, honey 1.42, butter 0.955.
Densities are approximate and temperature-dependent — a gallon of hot water weighs slightly less than a cold one, and powders vary with packing.
What 1 US gallon weighs
| Substance | Kilograms | Pounds |
|---|---|---|
| Water | 3.79 kg | 8.35 lb |
| Whole milk | 3.9 kg | 8.6 lb |
| Vegetable oil | 3.48 kg | 7.68 lb |
| All-purpose flour | 2.01 kg | 4.42 lb |
| Granulated sugar | 3.22 kg | 7.09 lb |
| Honey | 5.38 kg | 11.85 lb |
| Butter | 3.62 kg | 7.97 lb |
kg = 3.785411784 × density; lb = kg ÷ 0.45359237. Densities are approximate typical values.
Common mistakes
- Calling every gallon 8.34 lb — that is water; honey runs nearly 12 lb and flour under 4.5.
- Using the imperial gallon (4.546 L) with the US factor, inflating weight 20 percent.
- Forgetting the container: a filled 5-gallon bucket weighs the contents plus a pound or two of bucket.
- Treating kg/L and g/mL as different numbers — they are identical, so no extra conversion step exists.
Frequently asked questions
How much does a gallon of water weigh in kg?
About 3.79 kg, since a US gallon is 3.785 liters and water is close to 1 kg per liter. In pounds that is 8.35 lb.
What is the formula for gallons to kg?
kg = gallons × 3.785411784 × density in kg/L. For 5 gallons of water: 5 × 3.7854 × 1.00 = 18.93 kg.
Why does a gallon of milk weigh more than water?
Milk carries dissolved sugars, proteins, and minerals that make it about 3 percent denser than water — 1.03 kg/L — so the gallon jug weighs roughly 3.9 kg versus water's 3.79.
Does this work for UK imperial gallons?
No — an imperial gallon is 4.54609 liters, about 20 percent bigger. Multiply imperial gallons by 4.54609 × density instead; a UK gallon of water is about 4.55 kg.