Farming - 21 April 2023

Gallon to Litre Conversion Guide

How Many Litres in a Gallon?

If you’re wondering how many litres are in a gallon, here’s the simple answer:

• 1 US gallon = 3.785 litres
• 1 UK (Imperial) gallon = 4.546 litres

In Australia, the gallon usually refers to the imperial gallon, but most online references use US gallons, which can cause confusion when comparing measurements.

Gallons to Litres + Litres to Gallons Calculator

In this guide, we explain:

• How these conversions apply to water tank capacity
• How many litres are in a gallon
• The difference between US gallons and imperial gallons
• How to convert litres to gallons

Why This Matters in Australia

Australia uses the metric system, so water storage is measured in litres.

However, gallons are still used internationally, especially when comparing specifications for water tanks, pumps, or imported systems.

If you’re planning water storage, it’s important to convert correctly.
👉 Browse water tanks available in litres or visit the Tankworld homepage to explore Australian-made water storage solutions.

What is a gallon?

Let’s start at the beginning. A gallon is a unit of volume commonly used in the United States and several other countries. It is commonly used to measure liquids such as water, fuel and beverages.

One US gallon equals 3.785 litres.

In the US measurement system, one gallon is made up of:

• 4 quarts
• 8 pints
• 128 fluid ounces

Because Australia uses the metric system, Australians measure liquid capacity in litres. Especially when referring to rainwater tanks and water storage systems.

US Gallon vs Imperial Gallon (Australia)

Not all gallons are the same. While the definition of gallon is the same in both the United States and Australia, the actual volume of a gallon can differ between the two countries.

US Gallon

• 1 US gallon = 3.785 litres

Imperial Gallon (Used historically in Australia and the UK)

• 1 imperial gallon = 4.546 litres

This means the imperial (Australia) gallon is roughly 20% larger than the US gallon.

When converting gallons to litres, always use the correct conversion factor.

This can be a tricky difference to navigate if you’re travelling or doing business between the two countries, so make sure you’re clear on which type of gallon is being used!

Gallon to Litre Conversion

Now that we know the difference between American and Australian gallons, let’s talk about how to convert litres to Australian gallons.

Here are the most common conversion values.

• 1 US gallon = 3.785 litres
• 1 Australian gallon = 4.546 litres

This conversion guide below can help you estimate how much is 1 gallon to litres, litres to gallons, or how many litres in a US gallon

How to Convert Litres to Gallons

• Litres ÷ 3.785 = US gallons
• Litres ÷ 4.546 = UK gallons

To convert litres to gallons, divide the number of litres by the relevant conversion factor.

Example:

• 20 litres ÷ 3.785 = 5.28 US gallons
• 20 litres ÷ 4.546 = 4.40 imperial gallons

Check this conversion guide below for quick look how much litres to gallons

Why Gallon Conversions Matter for Water Tanks

When comparing international tank sizes or calculating storage capacity, understanding litres per gallon ensures accurate measurements.

Example:

• 1,000 gallons = 3,785 litres
• 5,000 gallons = 18,927 litres
• 10,000 gallons = 37,854 litres

In Australia, tanks are measured in litres, ranging from 330L to over 47,750L.

Use the conversion guide below to estimate water tank capacity.

Conversion Reference

• 1 US gallon = 3.785 litres
• 1 Australian / Imperial gallon = 4.546 litres

Because the imperial gallon is larger, litre-to-gallon conversions produce different results depending on the measurement system.

Choosing the Right Water Tank Size

If you’re converting gallons to litres for water storage, choosing the right size depends on:

• Property size
• Rainfall
• Water usage
• Available space

If you are calculating water storage capacity, explore our water tanks range from Small Water Tanks, Medium Water Tanks, and Large Water Tanks designed for Australian homes, farms and businesses.

Tankworld manufactures Australian-made tanks from 330 litres to over 47,750 litres, suitable for homes, farms and commercial use.

Our Water tanks from

Final Answer

If you only remember one thing:

👉 1 gallon = 3.785 litres (US) or 4.546 litres (UK)

While the concept of a gallon might seem like something we have all understood since primary school, this blog post has shown that there is a lot more to the humble gallon than meets the eye.

Whether you are researching fuel measurements, planning rainwater storage, or comparing tank sizes, knowing how many litres are in a gallon makes it easier to interpret specifications accurately.

So next time you’re faced with a gallon-related conundrum, you can confidently say, “I’ve got this.”

If you are planning a rainwater system, you can explore Tankworld’s Australian-made rainwater tanks and water storage designed for homes, farms and rural properties across Australia.

Frequently Ask Question about Litre to Gallon

Rewritten by

Diana Lestari