How Many Litres Are in a Gallon?

Do you want to get straight to the answer?

There are approximately 3.78541 litres in one gallon.

Liters and gallons are both unit measurements of volume and a gallon is commonly referred to as a standard distribution packaging of wine and corn harvest but it is rarely used, a liter on the other hand is internationally recognized and is widely used.

Since the two measurements are used by packaging companies; the package products adopt names depending on the unit of measurement used for instance, a gallon of oil, a liter of water, a gallon of fuel and so on.

Both the little and gallon are very common units of measurement so you ought to know how to differentiate between them.


What exactly is a gallon?

A gallon is a unit of liquid capacities. Quite different from other standard units of measurements, a gallon varies in size and as of now, there are three different known sizes of gallons. This unit of measurement is used in both the US customary and the British imperial systems of measurement.


What is a liter?

A liter too is a unit of liquid capacities usually confused to be the SI unit though it is not (the SI unit of volume is cm³. Liters were introduced in France and they were later adopted internationally, liters are a very common unit of measurement all over the globe.


The three different gallon sizes and their application.

1. The US liquid gallon

The US gallon is about 3.785 litres or 231 cubic inches and is commonly used in Latin America and the United States. Each US gallon is divide into 4 quarts, each quart is divided into 2 pints and each pint contains 16 US fluid ounces and therefore one US liquid gallon contains 128 US fluid ounces.

In order to overcome the changes in volume and mass that result from temperature changes, it is important and common to specify the temperature (and/ or pressure) at which a material weighs or the volume it occupies.


At 17°C, a US gallon of water is equivalent to 3.78kgs/ 8.34 pounds a US liquid gallon is 16.6% lighter than an imperial gallon.

The US Liquid gallon definition is adopted from the 19th Century British definition that basically related to volumes of wine.


1gallon = 4 quarts

But 1quart = 2 pints

(1 pint = 16 US fluid ounces.)

1 gallon = (4quarts × 2 pints)

= 8 pints.

From the table of units,

2 pints = 0.946 liters

1 pint = 0.946÷2

Therefore 8 pints = (0.946÷2) ×8

= 3.784 liters


2. The imperial gallon/ UK gallon

The imperial gallon is 4.54 liters and is commonly used in the common wealth states and Caribbean nations.

Initially, the imperial gallon was based on 10 pounds that equate to 4.54Kg of water at 17°C. An imperial fluid ounce weighs 1/160 of an imperial gallon.

Similar to the US liquid gallon, and an imperial gallon too is divided into 4 quarts with each quart contains 2 pints and each pint contains 20 imperial fluid ounces.

The Imperial gallon was adopted)l in 1824 by the British in UK and it was used until 1994 when the EU directive 80/181/EEC barred the use of gallons in trade and other official uses, favoring the use of liters instead.

The Caribbean nations and South America however still use this measurement.


According to the table of units,

2 pints = 1.134 liters

But a gallon contains 4quarts which each contain 2 pints.

1 gallon therefore = (2×4) pints

1 gallon is this.     = (1.134×4) liters

= 4.536 liters


3. The US dry gallon

The US dry gallon is equivalent to ⅛ US bushel and is also equivalent to 268.8025 cubic inches. The dry gallon is equivalent to 4.40488 liters.


Other definitions of the gallon-litre relation

Some individuals say that 1 gallon = 3+ (22÷7) ÷4 which is the same as [3+ (pi÷4]. This value is equivalent to 3.7854(4 decimal places). This value is an equivalent of only the US liquid gallon and is not applicable to other gallon measurements.


Calculated examples

1. Gallon-liter conversions

a) How many littles are in 20 US liquid gallons?

 Given that; 1 US liquid gallon = 3.785 literally

20 US liquid gallons = 3.785×20

= 75.7 literally


b) How many litres are in 5 dry gallons

Given that; 1 dry gallon = 4.40488 liters

5 dry gallons = (4.40488 × 5) liters

= 22.0244 liters


2. Liter – gallon conversions

a) How many US gallons are in a liter?

Given that; 1 US gallon = 3.785 literally

(x) US gallons = 1 liter

When cross multiplied,

(1). (1) = (3.785) (x)

x = 1÷ (3.785)

= 0.2642 gallons


b) How many UK/ imperial gallons are in 200 liters

Given that; 1 UK gallon = 4.54 liters

(y) UK gallons = 200 liters

When cross multiplied,

200 liters = (4.54) × (y)

Thus (y) = 200÷ (4.54)

= 44.053 gallons


Where are gallons still used?

Gallons are quite commonly used in America and in fact one of the questions you can use to test the observation skills of a male American is “how many littles are in a gallon?”

Because this value is printed on almost every male urinal and interestingly exactly where they are supposed to focus as they pee.

Gallons are mainly used in liquid processing industries like paint manufacturing factories, fuel pumps, and soft drink manufacturing companies and in wineries too. But only a few countries have remained using the gallon unit of measurements since the 90's when it was not allowed in use anymore.

Some of the countries that still use gallons are Peru, Palau, Dominican republic, Ecuador, Belize, Columbia among others.


Why were gallons phased out?

There are no clear reasons as to why the change was made but it is probable that the change was adopted because the prices of liquids in liters appear more affordable than those in gallons and therefore there would be greater chances of the liter-quantified liquids attracting more customers.


How to calculate the amount of gallons a tank can contain

In order to obtain the quantity of gallons that a tank can contain, you need to know the volume of your tank.

There are different ways of calculating volume and these depend on the shape of the material.

Below are the different ways which one can use to obtain the quantity of gallons contained in different shapes of tanks

a) Rectangular tank

Determine the gallon quantity of a rectangular tank will first require determination of the tank's volume.

  • Begin by measuring the outer length, width and height (L, W, H) of the tank in inches using a tape measure.
  • Measure the thickness (t) of the tank and subtract the value you obtain from the length, width and height of the tank; this is done in order to determine the inner length, width and height (L-t, W-t, H-t)
  • Determine the cubic volume by multiplying the length, width and height measurements

i.e.; volume= (L-t) × (W-t) × (H-t) in cubic inches

  • Then divide the cubic volume by 231 since a US gallon is equivalent to 231 cubic inches

The US gallon quantity will therefore be = [(L-t) × (W-t) × (H-t)] ÷231

Note: If you are considering the imperial gallon, you divide the volume by 277.42 cubic inches.


b) Cylindrical tank

For the cylindrical tank too, the volume has to determined first, and this is done by:

  • Measuring the radius R and inner height H of the cylinder using a tape measure in inches.
  • Determine the volume using the formula

V = (pi) (R²) (H)

Where pi is the constant 22/7

  • You can then determine the amount of gallons that can fit in the tank by dividing the volume by 231 or 277.42 cubic inches depending on which gallon quantity you are working with.



Conclusion: How Many Liters in a Gallon?

The most significant difference between a gallon and a litre is that a gallon is always greater than a litre regardless of whether it is a US gallon, an imperial gallon, or a dry gallon.

The litre and gallon were both official units of volume in the French metric system and the liter was adopted almost everywhere.

The fact remains that a liter is similar no matter where one goes but there is no standard quantity of a gallon since it varies according to where it is being used.

This makes it difficult for most individuals to adopt to using gallons when they get exposed to them.