How Much Does a Litre of Petrol Weigh? Gasoline Weight & Tank Guide

If you have ever carried a full 5-liter plastic fuel can from the filling station, you probably noticed that it feels surprisingly light compared to carrying a 5-liter jug of water.

That difference is not in your imagination. Petrol (motor gasoline) is substantially lighter than water.

1 Litre of Petrol (Gasoline) = 0.740 Kilograms (740 grams) Imperial Equivalent = 1.631 Pounds (lbs) = 26.1 Ounces Specific Gravity = 0.74 (Floating easily on water) 

At the international standard test temperature of 15°C (59°F), 1 litre of regular unleaded petrol weighs approximately 0.74 kilograms (1.63 pounds).

Because petrol is a blend of different volatile refined hydrocarbons, its density can vary slightly between 0.710 kg/L and 0.775 kg/L depending on octane rating, ethanol blend, and seasonal formulation.

Petrol Volume to Weight Breakdown Table

Here is the exact mass of common petrol volumes in metric (kilograms) and imperial (pounds) at a standard density of 0.740 kg/L:

Why Is Petrol So Light?

The reason a litre of petrol weighs only 740 grams comes down to organic chemistry.

Water (H₂O) has strong polar hydrogen bonds, packing its molecules tightly into a dense liquid lattice (1.00 kg/L). Petrol, on the other hand, consists of branched non-polar aliphatic hydrocarbons—primarily heptane (C7H16), octane (C8H18), and aromatics like toluene and benzene.

These carbon-hydrogen chains do not pack tightly, creating a lower molecular density:

• Water Density: 1.000 kg/L
• Diesel Density: 0.835 kg/L
• Petrol Density: 0.740 kg/L

Because petrol is 26% less dense than water, fuel spilled in water bodies does not sink; it forms a sheen on the surface.

What Affects the Weight of 1 Litre of Petrol?

Three main factors alter the exact weight of a litre of gasoline:

1. Ethanol Blending (E10 vs. E5 vs. Pure Petrol)

Most modern pump petrol contains fuel-grade anhydrous ethanol to reduce emissions:

• Pure Unblended Petrol (E0): ~0.730 to 0.740 kg/L
• Standard E10 (10% Ethanol): Ethanol has a density of 0.789 kg/L. Adding 10% ethanol increases overall density slightly to ~0.745 kg/L.
• E85 (85% Ethanol Flex-Fuel): High-blend ethanol fuels are notably heavier, averaging 0.780 kg/L.

2. Summer vs. Winter Blends

Refineries adjust the Reid Vapor Pressure (RVP) of petrol twice a year:

• Winter Blend: Formulated with more volatile, low-boiling-point hydrocarbons (like butane) to help engines start easily in sub-zero temperatures. Butane reduces density slightly (~0.725–0.735 kg/L).
• Summer Blend: Formulated with heavier, less volatile compounds to prevent vapor lock and evaporate less in hot weather, increasing density (~0.745–0.760 kg/L).

3. Ambient Fuel Temperature

Petrol possesses a high thermal expansion coefficient (β ≈ 0.0012 per °C). Here is how 1 litre of petrol changes in actual mass across temperatures:

To understand how temperature impacts freight and industrial processes, read our detailed guide on why temperature affects liquid density.

How Much Weight Does a Full Tank Add to Your Car?

Car manufacturers constantly fight to reduce vehicle curb weight for better fuel economy and handling. Fuel constitutes one of the largest variable weights in a passenger car.

• If you drive a 50-liter hatchback, filling an empty tank adds 37.0 kg (81.6 lbs).
• If you drive a 100-liter Ford F-150, filling from empty adds 74.0 kg (163.1 lbs)—equivalent to carrying an extra adult passenger in your vehicle.

This is why racing cars in Formula 1 and endurance motorsports calculate fuel loads to the milligram: carrying even 5 extra litres of fuel (3.7 kg) can cost up to 0.15 seconds per lap.

Frequently Asked Questions

Is petrol heavier than diesel?

No. Petrol is significantly lighter than diesel. One litre of petrol weighs 0.74 kg (1.63 lbs), whereas one litre of diesel weighs 0.835 kg (1.84 lbs). Diesel is roughly 13% heavier than petrol.

How much does 1 US gallon of gasoline weigh?

One US gallon equals 3.78541 litres. Multiplying by 0.74 kg/L gives 2.80 kg, which equals 6.18 pounds (lbs).

How many litres of petrol are in 1 kilogram?

Because density is 0.74 kg/L, dividing 1 by 0.74 gives approximately 1.351 litres of petrol per kilogram.

Need to convert specific fuel volumes or compare diesel and kerosene? Use our instant Petrol to Kg Calculator or view the broad comparisons in How Much Does Fuel Weigh?.