The Litre-to-Kg Formula
The mathematical conversion from volume (spatial capacity in litres) to gravitational mass (weight in kilograms) is governed by fundamental fluid mechanics. Density serves as the physical bridge connecting space to matter:
Mass (kg) = Volume (L) × Density (kg/L)
Or in abbreviated SI notation: m = V × ρ (where m = mass in kg, V = volume in litres, ρ = density in kg/L).
Depending on which two variables you know, the algebraic triangle can be rearranged into three forms:
- To find Mass (m):m = V × ρ (L × kg/L = kg)
- To find Volume (V):V = m ÷ ρ (kg ÷ kg/L = L)
- To find Density (ρ):ρ = m ÷ V (kg ÷ L = kg/L)
Step-by-Step Worked Example (Water → Milk → Diesel)
Let us convert 10 litres of three different fluids to see how physical density changes the resulting weight:
- • Volume (V) = 10.0 L
- • Density (ρ) = 1.000 kg/L
- • Calculation: 10 × 1.000
- = 10.000 kg
- • Volume (V) = 10.0 L
- • Density (ρ) = 1.030 kg/L
- • Calculation: 10 × 1.030
- = 10.300 kg (+300g)
- • Volume (V) = 10.0 L
- • Density (ρ) = 0.832 kg/L
- • Calculation: 10 × 0.832
- = 8.320 kg (-1,680g)
For algebraic derivation and physics proofs, review our deep-dive on the density formula V=m÷ρ explained.
Litres to Kg for the 10 Most Common Substances
Here is how 1 litre translates into kilograms across the 10 most frequently converted everyday and industrial liquids:
💧 Water1 Litre = 1.000 kg
Pure water at 4°C–20°C serves as the worldwide metric reference point. Exactly 1 litre of water equals 1.000 kg (1,000 grams).
🥛 Milk1 Litre = 1.030 kg
Whole cows' milk contains dissolved lactose sugars, casein proteins, and minerals that elevate liquid density to 1.030 kg/L (1,030g per litre).
🫒 Olive Oil1 Litre = 0.910 kg
Culinary olive oil is composed of long-chain fatty acid triglycerides, weighing only 910 grams per litre (9% lighter than water).
🍯 Honey1 Litre = 1.420 kg
Pure natural honey is a supersaturated sugar solution (>80° Brix), packing an incredible 1,420 grams into 1 single litre (42% heavier than water).
⛽ Diesel1 Litre = 0.832 kg
Standard automotive diesel (EN 590) has a calibrated density of 0.832 kg/L at 15°C, yielding 832 grams per litre at the dispensing nozzle.
🚗 Petrol / Gasoline1 Litre = 0.748 kg
Unleaded motor gasoline (95 RON / EN 228) consists of lightweight volatile hydrocarbons, weighing only 748 grams per litre.
🛢️ Engine Oil1 Litre ≈ 0.870 kg
Motor oils span from 0.845 kg/L (0W-20 synthetic) to 0.890 kg/L (20W-50 conventional), averaging ~0.870 kg/L across multigrade lubricants.
🧪 Ethanol / Alcohol1 Litre = 0.789 kg
Pure anhydrous ethyl alcohol (C₂H₅OH) has a low density of 0.789 kg/L (789 grams per litre) at standard laboratory conditions.
🧴 Glycerin / Glycerol1 Litre = 1.261 kg
USP pharmaceutical grade glycerol (99.5% purity) is dense and viscous, weighing 1,261 grams per litre.
💅 Acetone1 Litre = 0.784 kg
Industrial polar solvent acetone is highly volatile and light, weighing only 784 grams per litre (21.6% lighter than water).
Why Litres and Kilograms Are Not the Same Thing
What Density Means: Mass Per Unit of Space
The common assumption that "1 litre = 1 kg" is a metric convenience that applies only to pure water. A litre is a measure of geometric space (1,000 cubic centimetres), while a kilogram is a measure of gravitational matter. Density describes how closely packed atomic molecules are inside that 1-litre box.
Substances Lighter Than Water (Volume > Mass in kg)
When liquid density is below 1.000 kg/L, 1 litre weighs less than 1 kg. As a result, 1 kg of fuel or oil occupies more than 1 litre of volume (e.g. 1 kg of petrol = 1.337 L). These fluids float on top of water.
Substances Heavier Than Water (Volume < Mass in kg)
When liquid density is above 1.000 kg/L, 1 litre weighs more than 1 kg. Consequently, 1 kg occupies less than 1 litre of volume (e.g. 1 kg of honey = 0.704 L; 1 kg of 98% sulfuric acid = 0.545 L). These fluids sink below water.
How Temperature Affects the Litre-to-Kg Conversion
Why Warm Liquids Are Less Dense (Thermal Expansion)
Supplying thermal energy increases molecular kinetic vibration, causing liquid molecules to push farther apart. While the total mass of the fluid remains constant, the volume expands—lowering physical density as temperature climbs. Explore the complete physics in our guide on how temperature changes liquid density.
The 15°C Standard for Fuel Measurements (EN / ASTM)
Because hydrocarbon fuels expand by ~0.85% per 10°C, international oil logistics standardizes all custody transfer volume billing back to 15°C (59°F) using ASTM Table 54B Volume Correction Factors (VCF).
Cooking at Room Temperature: 20°C as Default Reference
Culinary formulation benchmarks use standard ambient kitchen temperature (20°C / 68°F). Heating frying oil to 180°C expands volume by ~10%, dropping operating density to ~0.81 kg/L.
Litre to Kg Conversion in Real-World Applications
1. Fuel Logistics and Customs Declarations
Bunkering barges and oil tankers declare cargo in metric tonnes for vessel draft stability and excise taxation, but discharge through volumetric litre flow meters. Accurate density conversion prevents massive customs billing disputes.
2. Commercial Cooking and Baking
Industrial food plants convert recipe volume instructions (litres) into automated digital scale dosing (kilograms) to eliminate jug meniscus reading errors and maintain precise product texture.
3. Chemical Manufacturing & Batching
Chemical reaction stoichiometry requires exact molar mass ratios. Converting raw chemical tank volumes into kilogram additions prevents dangerous exothermic imbalances and runaway reactions.
4. Agriculture: Sprayer Tank Mix Calculations
Liquid nitrogen fertilizers (such as UAN 32 at 1.32 kg/L) are 32% heavier than water. Calibrating crop sprayer flow rates strictly by volume would result in severe over-fertilization and crop damage.
Complete Litre to Kg Reference Table (50 Substances)
Verified mass values in kilograms across 1L, 5L, 10L, and 20L volume increments with citing standard references.
| Substance Name | Density @ Ref | 1 Litre | 5 Litres | 10 Litres | 20 Litres | Citing Standard |
|---|---|---|---|---|---|---|
| Pure WaterStandard at 4°C / 20°C | 1.000 kg/L | 1.000 kg | 5.000 kg | 10.000 kg | 20.000 kg | IUPAC / ISO 3696 |
| Sea Water (Saline)3.5% average salinity | 1.025 kg/L | 1.025 kg | 5.125 kg | 10.250 kg | 20.500 kg | UNESCO Oceanographic |
| Whole Milk (3.5% fat)Commercial dairy standard | 1.030 kg/L | 1.030 kg | 5.150 kg | 10.300 kg | 20.600 kg | Codex Alimentarius |
| Skim Milk (0.1% fat)Non-fat dairy | 1.036 kg/L | 1.036 kg | 5.180 kg | 10.360 kg | 20.720 kg | USDA FoodData |
| Heavy Whipping Cream (38% fat)High butterfat emulsion | 0.994 kg/L | 0.994 kg | 4.970 kg | 9.940 kg | 19.880 kg | USDA FoodData |
| Extra Virgin Olive OilCold-pressed culinary oil | 0.910 kg/L | 0.910 kg | 4.550 kg | 9.100 kg | 18.200 kg | IOC / Codex |
| Canola / Rapeseed OilRefined frying oil | 0.918 kg/L | 0.918 kg | 4.590 kg | 9.180 kg | 18.360 kg | Codex-Stan 210 |
| Sunflower Seed OilPolyunsaturated cooking oil | 0.920 kg/L | 0.920 kg | 4.600 kg | 9.200 kg | 18.400 kg | Codex-Stan 210 |
| Coconut Oil (Liquid @ 30°C)Medium-chain triglycerides | 0.924 kg/L | 0.924 kg | 4.620 kg | 9.240 kg | 18.480 kg | USDA FoodData |
| Peanut / Groundnut OilHigh smoke-point oil | 0.914 kg/L | 0.914 kg | 4.570 kg | 9.140 kg | 18.280 kg | Codex-Stan 210 |
| Pure Natural Honey>80° Brix natural sweetener | 1.420 kg/L | 1.420 kg | 7.100 kg | 14.200 kg | 28.400 kg | Codex-Stan 12 |
| Pure Maple Syrup (Grade A)66° Brix concentrated sap | 1.325 kg/L | 1.325 kg | 6.625 kg | 13.250 kg | 26.500 kg | USDA Standards |
| Blackstrap MolassesDense cane sugar byproduct | 1.410 kg/L | 1.410 kg | 7.050 kg | 14.100 kg | 28.200 kg | USDA FoodData |
| Corn Syrup (High Fructose 55)Commercial baking syrup | 1.380 kg/L | 1.380 kg | 6.900 kg | 13.800 kg | 27.600 kg | Corn Refiners Assoc |
| Automotive Diesel (EN 590)Standard middle distillate @ 15°C | 0.832 kg/L | 0.832 kg | 4.160 kg | 8.320 kg | 16.640 kg | EN 590 / ASTM D975 |
| Unleaded Petrol / Gasoline (95 RON)Standard European motor fuel @ 15°C | 0.748 kg/L | 0.748 kg | 3.740 kg | 7.480 kg | 14.960 kg | EN 228 / ASTM D4814 |
| Premium Super Unleaded (98 RON)High aromatic octane blend | 0.755 kg/L | 0.755 kg | 3.775 kg | 7.550 kg | 15.100 kg | EN 228 |
| E10 Petrol (10% Ethanol Blend)Standard pump gasoline | 0.752 kg/L | 0.752 kg | 3.760 kg | 7.520 kg | 15.040 kg | EN 228 / ASTM D4814 |
| E85 Flex-Fuel (85% Ethanol)High ethanol renewable fuel | 0.782 kg/L | 0.782 kg | 3.910 kg | 7.820 kg | 15.640 kg | ASTM D5798 |
| Kerosene (Domestic Heating / Jet)BS 2869 Class C2 | 0.810 kg/L | 0.810 kg | 4.050 kg | 8.100 kg | 16.200 kg | ASTM D3699 |
| Jet A-1 Aviation Turbine FuelCommercial aviation fuel | 0.804 kg/L | 0.804 kg | 4.020 kg | 8.040 kg | 16.080 kg | ASTM D1655 / DEF STAN |
| Biodiesel (B100 FAME)Fatty acid methyl ester | 0.880 kg/L | 0.880 kg | 4.400 kg | 8.800 kg | 17.600 kg | EN 14214 / ASTM D6751 |
| Heavy Fuel Oil (HFO / Bunker C)Marine propulsion bunker fuel | 0.960 kg/L | 0.960 kg | 4.800 kg | 9.600 kg | 19.200 kg | ISO 8217 |
| Engine Oil (SAE 0W-20 Full Synth)PAO synthetic lubricant | 0.845 kg/L | 0.845 kg | 4.225 kg | 8.450 kg | 16.900 kg | SAE J300 / API SP |
| Engine Oil (SAE 5W-30 Synthetic)Standard passenger car oil | 0.855 kg/L | 0.855 kg | 4.275 kg | 8.550 kg | 17.100 kg | SAE J300 / API SP |
| Engine Oil (SAE 10W-40 Semi-Synth)Part synthetic blend | 0.872 kg/L | 0.872 kg | 4.360 kg | 8.720 kg | 17.440 kg | SAE J300 |
| Engine Oil (SAE 15W-40 Heavy Duty)Commercial diesel engine oil | 0.880 kg/L | 0.880 kg | 4.400 kg | 8.800 kg | 17.600 kg | API CK-4 / CJ-4 |
| Engine Oil (SAE 20W-50 Mineral)High-viscosity classic engine oil | 0.890 kg/L | 0.890 kg | 4.450 kg | 8.900 kg | 17.800 kg | SAE J300 |
| Automatic Transmission Fluid (ATF)Dexron VI / Mercon LV | 0.860 kg/L | 0.860 kg | 4.300 kg | 8.600 kg | 17.200 kg | GM / Ford Spec |
| DOT 4 Brake FluidGlycol ether based hydraulic | 1.050 kg/L | 1.050 kg | 5.250 kg | 10.500 kg | 21.000 kg | FMVSS 116 / ISO 4925 |
| Engine Coolant / Antifreeze (50/50)50% Ethylene glycol aqueous | 1.065 kg/L | 1.065 kg | 5.325 kg | 10.650 kg | 21.300 kg | ASTM D3306 |
| Pure Ethylene Glycol (100%)Industrial coolant concentrate | 1.113 kg/L | 1.113 kg | 5.565 kg | 11.130 kg | 22.260 kg | CRC Handbook |
| Pure Propylene Glycol (USP)Non-toxic food grade chiller fluid | 1.036 kg/L | 1.036 kg | 5.180 kg | 10.360 kg | 20.720 kg | USP / EP Monograph |
| Pure Glycerin / Glycerol (99.5%)Heavy viscous humectant | 1.261 kg/L | 1.261 kg | 6.305 kg | 12.610 kg | 25.220 kg | USP / Ph. Eur. |
| Acetone (HPLC / Tech Grade)Volatile polar solvent (UN 1090) | 0.784 kg/L | 0.784 kg | 3.920 kg | 7.840 kg | 15.680 kg | ASTM D329 / CRC |
| Ethanol (100% Anhydrous Alcohol)Absolute ethyl alcohol (UN 1170) | 0.789 kg/L | 0.789 kg | 3.945 kg | 7.890 kg | 15.780 kg | USP / BP Standards |
| Ethanol (96% Azeotropic / Rectified)Distilled spirit / disinfectant | 0.806 kg/L | 0.806 kg | 4.030 kg | 8.060 kg | 16.120 kg | Ph. Eur. |
| Isopropyl Alcohol (99% IPA)Precision electronic solvent (UN 1219) | 0.786 kg/L | 0.786 kg | 3.930 kg | 7.860 kg | 15.720 kg | ASTM D770 |
| Methanol (Methyl Alcohol 99.9%)Industrial solvent (UN 1230) | 0.792 kg/L | 0.792 kg | 3.960 kg | 7.920 kg | 15.840 kg | IMPCA Standard |
| Toluene (Methylbenzene 99.8%)Aromatic solvent (UN 1294) | 0.867 kg/L | 0.867 kg | 4.335 kg | 8.670 kg | 17.340 kg | ASTM D841 |
| Xylene (Mixed Isomers 99%)Paint solvent & thinner (UN 1307) | 0.864 kg/L | 0.864 kg | 4.320 kg | 8.640 kg | 17.280 kg | ASTM D843 |
| Sulfuric Acid (98% Concentrated)Heavy mineral acid (UN 1830) | 1.836 kg/L | 1.836 kg | 9.180 kg | 18.360 kg | 36.720 kg | ISO 9001 / CRC |
| Sulfuric Acid (33.5% Battery Grade)Lead-acid battery electrolyte (UN 2796) | 1.250 kg/L | 1.250 kg | 6.250 kg | 12.500 kg | 25.000 kg | BCI Standard |
| Nitric Acid (68% Concentrated)Oxidizing mineral acid (UN 2031) | 1.410 kg/L | 1.410 kg | 7.050 kg | 14.100 kg | 28.200 kg | ACS Reagent Grade |
| Hydrochloric Acid (37% Muriatic)Concentrated aqueous HCl (UN 1789) | 1.190 kg/L | 1.190 kg | 5.950 kg | 11.900 kg | 23.800 kg | ASTM E1146 |
| Phosphoric Acid (85% Food/Tech)Food acidulant / rust converter (UN 1805) | 1.685 kg/L | 1.685 kg | 8.425 kg | 16.850 kg | 33.700 kg | Food Chemicals Codex |
| Sodium Hydroxide (50% Liquid Lye)Caustic soda solution (UN 1824) | 1.525 kg/L | 1.525 kg | 7.625 kg | 15.250 kg | 30.500 kg | ASTM E291 |
| Potassium Hydroxide (45% Solution)Liquid caustic potash (UN 1814) | 1.450 kg/L | 1.450 kg | 7.250 kg | 14.500 kg | 29.000 kg | ACS Reagent Grade |
| Aqueous Ammonia (28% NH₄OH)Technical alkaline solution (UN 2672) | 0.898 kg/L | 0.898 kg | 4.490 kg | 8.980 kg | 17.960 kg | ASTM D1426 |
| Liquid Fertilizer (UAN 32)32% Nitrogen solution for crop spray | 1.320 kg/L | 1.320 kg | 6.600 kg | 13.200 kg | 26.400 kg | TFI / ISO Standards |
Explore Universal Conversion Network
Frequently Asked Questions
Common practical questions on converting litres to kilograms.