How Many Litres in a Gallon in Australia

Understanding how many litres are in a gallon in Australia is important when dealing with water storage, fuel measurements, rainwater tanks, or imported equipment that still uses gallons as a unit of measurement.

How Many Litres Are in a Gallon?

In Australia, we use the metric system, so litres are the standard unit of measurement. However, the term “gallon” can mean different things depending on the country.

Gallon to Litre Conversions

• 1 Australian (Imperial) gallon = 4.546 litres

• 1 US gallon = 3.785 litres

⚠️ This distinction is critical, as many products and specifications online reference US gallons, not imperial gallons.

Why This Matters in Australia

When purchasing or comparing:

• Water tanks

• Pumps and irrigation systems

• Chemical or liquid storage

• Imported equipment

Using the wrong gallon conversion can result in:

• Incorrect capacity calculations

• Undersized or oversized systems

• Compliance and installation issues

Quick Reference Conversion Table

• 10 gallons (US) = 37.85 litres

• 10 gallons (Imperial) = 45.46 litres

• 100 gallons (US) = 378.5 litres

• 100 gallons (Imperial) = 454.6 litres

Metric Measurements Are the Australian Standard

In Australia:

• Water tanks are sold in litres (L)

• Rainwater harvesting regulations reference litres or kilolitres

• Plumbing and building codes use metric units only

If you’re converting gallons to litres for water storage, always confirm which gallon is being referenced.