How to convert litres to kilograms
Converting litres to kilograms is not a one-size-fits-all calculation. A litre is a unit of volume, while a kilogram is a unit of mass. To connect the two, you need one extra piece of information: density.
The density of a substance tells you how many kilograms fit into one litre. Water is the easiest example because it is very close to 1 kg per litre at room temperature, but oils, fuels, syrups, and chemicals can vary a lot.
litres to kg formula
kg = L × density (kg/L)
- L = volume in litres
- density = mass per litre in kg/L
- kg = result in kilograms
Quick examples
- 10 litres of water: 10 × 1.000 = 10.00 kg
- 10 litres of olive oil: 10 × 0.910 = 9.10 kg
- 10 litres of honey: 10 × 1.420 = 14.20 kg
Common densities (approximate)
Use the table below when you need a fast estimate. For industrial, food, or scientific tasks, always use the density from your datasheet at the relevant temperature.
| Substance | Density (kg/L) | 1 L in kg |
|---|---|---|
| Water | 1.000 | 1.000 kg |
| Milk | 1.030 | 1.030 kg |
| Seawater | 1.025 | 1.025 kg |
| Olive oil | 0.910 | 0.910 kg |
| Diesel | 0.840 | 0.840 kg |
| Gasoline | 0.740 | 0.740 kg |
| Ethanol | 0.789 | 0.789 kg |
| Honey | 1.420 | 1.420 kg |
Step-by-step method
1) Enter volume in litres
Start with the liquid volume you have, such as 2.5 L, 18 L, or 250 L.
2) Find the correct density in kg/L
Use a known value from a trusted source. If you are using this calculator for rough everyday conversions, the presets are often enough.
3) Multiply litres by density
The product is your mass in kilograms. If needed, round the result to 2 or 3 decimal places for readability.
Why your litres-to-kg result may differ
- Temperature changes density: warmer liquids are often less dense.
- Composition varies: products like milk, fuel, and syrup differ by brand or grade.
- Rounding: using rounded density values introduces small differences.
- Mixtures: blended liquids do not always behave like pure substances.
Frequently asked questions
Is 1 litre always 1 kilogram?
No. That is only true (approximately) for water near room temperature. Most liquids are heavier or lighter than water.
Can I use this for solids?
Yes, if the solid is measured by volume and you know its bulk density in kg/L. Otherwise, use a method specific to solid materials.
Do I need high precision?
For cooking and everyday tasks, approximate density is usually fine. For engineering, transport, pharma, and lab work, use precise, temperature-corrected data.
Final tip
If your goal is speed, choose a preset density and convert in one click. If your goal is accuracy, select Custom density and enter a value from your technical data sheet.