What is the difference between US and UK gallons?

A US gallon is 3.785 liters, while a UK (Imperial) gallon is 4.546 liters—about 20% larger.

How many liters in 5 gallons?

5 US gallons equals approximately 18.93 liters.

How many liters of gas is a full tank?

Average car tanks hold 12-16 gallons, which equals 45-60 liters.

What is a gallon of milk in liters?

A gallon of milk equals approximately 3.79 liters. Milk in other countries is often sold in 1L, 2L, or 4L containers.

Gallons to Liters Converter | gal to L Calculator

Conversion Formula

L = gal × 3.78541

To convert US gallons to liters, multiply the gallon value by 3.78541. One US gallon equals approximately 3.785 liters.

Complete Guide to Gallons (US) to Liters Conversion

What is a Gallons (US)?

A US gallon (gal) is a unit of volume equal to 128 fluid ounces, 4 quarts, or 231 cubic inches. It is used in the United States for measuring fuel, beverages, and other liquids.

What is a Liters?

A liter (L) is a metric unit of volume equal to 1,000 milliliters or 1 cubic decimeter. It is the standard volume measure in most of the world for liquids and gases.

How the Conversion Works

The conversion factor 3.78541 comes from the definition of a US gallon as exactly 231 cubic inches, which equals 3.785411784 liters.

Why This Conversion Matters

Understanding this conversion is essential for comparing fuel prices internationally, following recipes from different countries, and working with industrial liquid quantities.

Scientific Context

The liter is part of the metric system and relates directly to the meter (1 L = 1 dm³). While not an SI unit, it is accepted for use with the SI system.

Step-by-Step Conversion Guide

Follow these steps to convert gallons (us) to liters manually:

Start with your value in gallons (us)

Example: You want to convert 5 gal

Apply the conversion formula

Use the formula: L = gal × 3.78541

Calculate the result

5 gal = 18.9271 L

✓

Verify your answer

Use our calculator above to double-check your manual calculation.

Quick Mental Math Tip

To convert US gallons to liters, multiply the gallon value by 3.78541. One US gallon equals approximately 3.785 liters.

Common Conversions

Gallons (US) to Liters conversion table
Gallons (US) (gal)	Liters (L)	Liters → Gallons (US)
1 gal	3.7854	1 L = 0.2642 gal
2 gal	7.5708	2 L = 0.5283 gal
5 gal	18.9271	5 L = 1.3209 gal
10 gal	37.8541	10 L = 2.6417 gal
15	56.7812	15 L = 3.9626 gal
20 gal	75.7082	20 L = 5.2834 gal
50 gal	189.2705	50 L = 13.2086 gal
100	378.541	100 L = 26.4172 gal
500	1892.705	500 L = 132.0861 gal
1000	3785.41	1000 L = 264.1722 gal

Did You Know?

The liter was originally defined as the volume of 1 kilogram of water at 4°C, creating a direct link between volume and weight measurements.

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Popular Gallons (US) to Liters Conversions

1 gal= 3.79 L 2 gal= 7.57 L 3 gal= 11.36 L 5 gal= 18.93 L 10 gal= 37.85 L 20 gal= 75.71 L 50 gal= 189.27 L

When You'll Need This Conversion

Fuel Purchases

Understand fuel prices and tank capacity when traveling to countries that sell fuel in liters.

Pool & Tank Sizing

Convert swimming pool volumes, water tank capacities, and aquarium sizes between systems.

Bulk Cooking

Convert large recipe quantities and catering measurements between gallons and liters.

Industrial Applications

Convert liquid chemical quantities, paint volumes, and manufacturing specifications.

Pro Tips for Accurate Conversions

Multiply by 4 for quick estimates

1 gallon ≈ 4 liters (actual: 3.785). This overestimates by about 5% but is easy to remember.

For fuel economy conversions

When comparing MPG to L/100km, remember that higher MPG means lower L/100km (better efficiency).

US vs Imperial gallon

Always confirm which gallon is meant. UK/Imperial gallons are 20% larger. This converter uses US gallons.

Common Mistakes to Avoid

Confusing US and Imperial gallons

A US gallon (3.785 L) is smaller than a UK Imperial gallon (4.546 L). Using the wrong one gives a 20% error.

Confirm which gallon system is being used. This converter uses US gallons.

Using 4 liters per gallon for precise calculations

While 4 L/gallon is easy to remember, it overestimates by 5.7%.

Use 3.785 for accurate results: 10 gal × 3.785 = 37.85 L, not 40 L.

History & Background

The gallon has medieval origins and varied widely between regions. The US gallon was standardized in 1832, while the UK Imperial gallon was defined in 1824.

Key Milestones

1824

The UK Imperial gallon was defined as the volume of 10 pounds of water (4.546 liters).

1832

The US gallon was standardized as 231 cubic inches (3.785 liters), based on the old English wine gallon.

1960s

Most countries adopted the liter as part of metrication programs.

Global Usage Today

The gallon is primarily used in the United States. The UK uses liters for fuel but gallons are still understood. Most other countries use liters exclusively.