Gallons to Liters Converter
Convert US gallons to liters, milliliters and fluid ounces.
How to use this gallons to liters
- 1Enter your volume in US gallons.
- 2The converter shows liters, milliliters, and fluid ounces instantly.
- 3For fuel tank comparisons between US and international vehicles, convert gallon capacity to liters.
- 4For fuel economy: a car rated at 30 mpg US would need to travel 30 miles per 3.785 liters — the L/100km equivalent is 7.84 L/100km.
- 5For water usage and container sizing, 1 US gallon = 3.785 L = 3,785 ml.
- 6Key note: the UK imperial gallon (4.546 L) is about 20% larger — always confirm which gallon is referenced.
How it's calculated
liters = US gallons × 3.78541. 1 US gal = 3.78541 L.
About the Gallons to Liters
The gallon is a large volume unit used primarily in the United States for fuel, water, beverages, and many industrial applications. It is one of the most internationally confusing units because the US gallon (3.78541 liters) and the UK imperial gallon (4.54609 liters) share a name but represent significantly different volumes — the imperial gallon is approximately 20% larger.
Fuel economy is the most economically significant context for gallons-to-liters conversion. US fuel efficiency is measured in miles per gallon (mpg); most of the world uses liters per 100 kilometers (L/100km). Converting between these systems for cross-market vehicle comparisons requires both gallon-to-liter conversion and mile-to-km conversion. The formula is L/100km = 235.215 ÷ mpg (US), and mpg (US) = 235.215 ÷ L/100km. A 30 mpg US rating = 7.84 L/100km; a 6 L/100km European rating = 39.2 mpg US.
Fuel tank capacity comparisons are another practical use case. A US vehicle with a "16-gallon tank" holds 60.6 liters; a European vehicle with a "60-liter tank" holds 15.85 US gallons. When shopping for vehicles across markets, converting tank capacity allows apples-to-apples comparison of range. Combined with fuel economy, this determines the real-world range between fill-ups.
Water and liquid storage use gallons in the US context. Common references: a standard US water bottle is 0.5 gallons (1.89 L), a typical bottled water jug is 1 gallon (3.785 L), a 5-gallon water cooler jug is 18.93 liters. For outdoor activities, hydration calculations in the US use gallons or fluid ounces while international hiking guides use liters. A person's daily water intake recommendation of 2.7–3.7 liters = approximately 0.71–0.98 gallons.
Commercial and industrial quantities in the US are expressed in gallons for paint, chemicals, cleaning products, agricultural inputs, and many other categories. A 5-gallon bucket (a ubiquitous US construction and hardware reference) is 18.93 liters. A 55-gallon drum (the standard industrial container) is 208.2 liters. International equivalents use 200-liter barrels (52.8 US gallons) — close but not identical, making precise conversion necessary when comparing specifications.
Frequently asked questions
How many liters is 1 US gallon?
1 US gallon = 3.78541 liters exactly. The UK imperial gallon = 4.54609 liters — about 20% more. Common reference: 5 gallons = 18.93 L, 10 gallons = 37.85 L, 20 gallons = 75.71 L.
How many gallons is 10 liters?
10 ÷ 3.78541 = 2.642 US gallons. Common: 4 L ≈ 1.06 gallons, 20 L = 5.28 gallons, 50 L = 13.21 gallons.
How do I convert mpg (US) to L/100km?
L/100km = 235.215 ÷ mpg (US). Example: 30 mpg = 235.215 ÷ 30 = 7.84 L/100km. Alternatively: 25 mpg = 9.41 L/100km, 35 mpg = 6.72 L/100km, 40 mpg = 5.88 L/100km.
How many gallons is a standard swimming pool?
A standard residential pool (12 × 24 ft, 5 ft average depth) holds approximately 10,800 gallons = 40,878 liters. An Olympic pool (50m × 25m × 2m deep) holds 2,500,000 liters = 660,430 US gallons.
Why does the US gallon differ from the UK gallon?
The US gallon (3.785 L) derives from the old English wine gallon, while the UK imperial gallon (4.546 L) was standardized in 1824 based on the volume of 10 pounds of water at a specific temperature. Both derived from historical English measures but diverged when the UK reformed its measurement system post-independence from colonial alignment. The 20% difference means fuel efficiency comparisons between US and UK vehicles require careful unit clarification.