kg to Liter Converter: Convert Weight to Volume by Substance
Kilograms measure mass; liters measure volume. The two are only equal when the substance has a density of exactly 1 kg/L, which is pure water. For everything else, divide mass by density to get volume, or multiply volume by density to get mass. Select your substance (or enter a custom density), enter kilograms or liters, and the result appears instantly with the full calculation shown.
Why kilograms and liters are not the same
Kilograms are a unit of mass: they tell you how much matter is present. Liters are a unit of volume: they describe how much space that matter occupies. These two quantities are only numerically equal when the substance has a density of exactly 1 kg/L, which is the case for pure water at 4 degrees Celsius. Every other liquid or solid has a different density, so the relationship between its mass and its volume differs from the water baseline. A liter of honey weighs about 1.42 kg because honey is much denser than water. A liter of gasoline weighs only about 0.74 kg because gasoline is less dense. To convert between kilograms and liters for any substance, you need to know its density in kg/L.
The conversion formula
The formula is a direct rearrangement of the density definition. Density (in kg/L) equals mass (in kg) divided by volume (in liters). Rearranging that gives the two conversion directions: To convert kg to liters: liters = kg / density To convert liters to kg: kg = liters x density For example, to convert 5 kg of honey to liters, divide by the density of honey (1.42 kg/L): 5 / 1.42 = 3.52 liters. To go the other way, 3.52 liters of honey weighs 3.52 x 1.42 = 5 kg. The calculator above handles both directions and carries the calculation through to milliliters, cubic meters, and grams so you do not have to do the unit bookkeeping manually.
How to use a custom density
The preset substance list covers the most common liquids, but many industrial, scientific, and culinary applications involve materials not on the list. To handle those, select "Custom density" from the substance dropdown and type in the density value from your material safety data sheet, product specification, or reference table. The density must be in kg/L (equivalently, g/mL or t/m3 - all three are numerically identical). If your source gives density in kg/m3, divide by 1000 to get kg/L. If it gives density in lb/gal, multiply by 0.1198 to get kg/L.
Common cooking conversions
In cooking and baking, recipes often call for ingredients by weight (grams or kilograms) but measuring cups measure volume (milliliters or liters). The density values in this calculator let you switch between the two. Water and most thin broths sit at about 1 kg/L, so 1 cup (237 mL) of water weighs about 237 g. Milk is slightly denser (1.031 kg/L), so the same cup of whole milk weighs about 244 g. Oils are lighter than water (around 0.88-0.92 kg/L), so 1 cup of cooking oil weighs only about 200-215 g. Honey is much denser (1.42 kg/L), so 1 cup weighs about 340 g, significantly more than the same volume of water.
Density of common substances
| Substance | Density (kg/L) | Type |
|---|---|---|
| Water (pure) | 1 | Reference |
| Milk | 1.031 | Dairy |
| Buttermilk | 1.033 | Dairy |
| Heavy cream | 1.012 | Dairy |
| Yogurt | 1.05 | Dairy |
| Honey | 1.42 | Food |
| Salt water | 1.025 | Food |
| Juice | 1.045 | Food |
| Beer | 1.004 | Beverage |
| Wine | 0.994 | Beverage |
| Vinegar | 1.006 | Food |
| Cooking oil | 0.88 | Oil |
| Olive oil | 0.918 | Oil |
| Sunflower oil | 0.92 | Oil |
| Butter | 0.911 | Dairy |
| Gasoline | 0.74 | Fuel |
| Diesel | 0.85 | Fuel |
| Kerosene | 0.82 | Fuel |
| Engine oil | 0.87 | Industrial |
| Crude oil | 0.87 | Industrial |
| Bleach | 1.08 | Chemical |
| Paint | 1.2 | Industrial |
Approximate densities at room temperature (~20 degrees C). Actual values vary with temperature and purity.
Frequently asked questions
Is 1 kg always equal to 1 liter?
No. The 1-to-1 relationship only holds for pure water at its maximum density (4 degrees Celsius). Every other substance has a different density, so 1 kg will occupy either more or less than 1 liter. For example, 1 kg of gasoline fills about 1.35 L because gasoline is less dense than water, while 1 kg of honey fills only about 0.70 L because honey is much denser.
How do I convert kg to liters for milk?
Whole milk has a density of approximately 1.031 kg/L. Divide the mass in kilograms by 1.031 to get liters. For example, 2 kg of milk is 2 / 1.031 = 1.94 liters, or about 1,940 mL. The exact density can vary slightly depending on fat content, so skim milk (1.033 kg/L) and cream have slightly different values.
How do I convert kg to liters for cooking oil?
Most cooking oils have a density in the range of 0.88-0.92 kg/L. Divide the mass in kilograms by the density. For generic cooking oil at 0.880 kg/L, 1 kg is 1 / 0.880 = 1.136 liters. Olive oil (0.918 kg/L) gives 1 / 0.918 = 1.089 liters per kilogram. Because oils are less dense than water, a given mass of oil always occupies more volume than the same mass of water.
What is the formula to convert liters to kg?
Multiply the volume in liters by the density of the substance in kg/L. The formula is: kg = liters x density. For water (density = 1.000), liters and kilograms are equal. For honey (density = 1.420), 5 liters of honey weighs 5 x 1.420 = 7.10 kg. Use the liter-to-kg mode in this calculator to handle the arithmetic for any substance on the list.
Why does temperature affect the conversion?
Most substances expand when heated and contract when cooled, which changes their density. Water, for example, is densest at 4 degrees Celsius (density 1.000 kg/L) but at 100 degrees Celsius its density drops to about 0.958 kg/L, so 1 kg of boiling water occupies about 1.044 liters. The density values in this calculator are standard at approximately 20 degrees Celsius (68 degrees Fahrenheit). For precision work at other temperatures, look up the specific density for your temperature and use the custom density option.
How do I convert kg/m3 to kg/L for the custom density field?
Divide the value in kg/m3 by 1000. For example, if your data sheet says a substance has a density of 850 kg/m3, enter 0.850 in the custom density field (kg/L). This works because 1 m3 = 1000 liters, so dividing by 1000 converts the volume unit from cubic meters to liters.