US Gallons to Liters Converter - Free Online Tool

Convert US liquid, Imperial, and dry gallons to liters — and back — with full formula transparency

The US Gallons to Liters Converter is an essential tool for anyone dealing with volume measurements across different systems of measurement. Whether you are a driver calculating fuel capacity, a home brewer measuring ingredients, a scientist working in a lab, or a traveler trying to understand foreign fuel prices, knowing how to convert gallons to liters — and liters back to gallons — is a practical, everyday skill. The United States primarily uses the gallon as a standard unit of liquid volume, while most of the rest of the world uses the liter, the SI (International System of Units) standard. This difference creates constant need for conversion in trade, cooking, manufacturing, fuel economy comparisons, and international shipping. Our converter handles all three types of gallon — the US liquid gallon, the US dry gallon, and the Imperial (UK) gallon — making it the most complete tool for anyone who deals with volume across borders or industries. The US liquid gallon is the most commonly referenced gallon in everyday American life. It is legally defined as exactly 231 cubic inches, which equals 3.785411784 liters. You encounter this gallon at gas stations, in milk jugs, paint cans, and water jugs. The Imperial gallon, used in the United Kingdom, Canada, and parts of the Caribbean, is larger — it equals approximately 4.54609 liters, or about 20% more than the US gallon. Confusing the two can cause significant errors in cooking, fuel calculations, and fluid transfers. The US dry gallon, defined as 268.8025 cubic inches or 4.40488 liters, is less common and historically used for measuring dry goods such as grains and berries, though it is largely replaced by weight measurements in modern practice. This converter also supports bidirectional conversion. You can enter a value in gallons and get the liter result, or enter a value in liters and instantly see the gallon equivalent. This flexibility is especially useful for international travelers, importers and exporters, and anyone comparing product specifications between metric and imperial catalogs. The precision selector lets you control how many decimal places appear in your results — 2 places for quick estimates, 4 places for standard engineering and cooking use, or 6 places for scientific accuracy. The formula display shows the exact calculation used, so you can understand and verify the math yourself. For bulk work, the batch conversion mode lets you enter a comma-separated list of gallon values and receive all the results at once, saving time when processing lists of measurements. The reference examples panel provides real-world context for your conversions. Knowing that a standard US fuel tank holds roughly 13 to 16 gallons (about 49 to 60 liters), or that a 55-gallon drum holds 208.2 liters, makes the numbers more meaningful and easier to sanity-check. The preset conversion table gives you instant access to the most commonly needed gallon-to-liter values from 0.5 gallons all the way to 1,000 gallons, displayed alongside both liter and Imperial gallon equivalents. All calculations run entirely in your browser. No data is sent to any server, and nothing is stored. The results are private and instant. You can also print the results or export them to CSV for use in spreadsheets, reports, or documentation. Whether you need a single quick conversion or a batch of hundreds, this tool is designed to give you fast, accurate, and verifiable results every time.

Understanding Gallons and Liters

The gallon and the liter are both units of liquid volume, but they come from entirely different measurement traditions. Understanding the differences between gallon types — and why the conversion factor matters — helps you use this tool with confidence.

The Three Types of Gallon

There are three distinct gallon measurements in use today, and confusing them can cause meaningful errors. The US liquid gallon (3.785411784 L) is the standard for everyday American use — gas stations, grocery stores, and product packaging all use this definition. The Imperial gallon (4.54609188 L), used in the UK, Canada, and some Caribbean nations, is about 20% larger than the US gallon. This difference is critical when comparing fuel economy between US miles per gallon and UK miles per gallon. The US dry gallon (4.40488377 L) is a historic unit used for measuring dry commodities like grain and fruits — it is rarely encountered today but is still legally defined. When performing any gallon-to-liter conversion, always confirm which gallon type is intended to avoid systematic errors.

The Liter and the Metric System

The liter (also spelled litre) is the metric unit of volume most commonly used in everyday life worldwide. It is formally defined as one cubic decimeter — a cube that is 10 centimeters on each side, with a volume of exactly 1,000 cubic centimeters. The liter is part of the International System of Units (SI), which traces its origins to the French Revolution when standardized measurement was established to replace dozens of conflicting regional standards. Today, all countries except the United States, Liberia, and Myanmar have officially adopted the metric system as their primary standard. In practice, liters are used globally for beverages, fuel, household products, and scientific measurements. One liter of pure water at standard temperature weighs exactly one kilogram, which is a useful practical relationship to remember.

Why the Conversion Factor Matters

The exact conversion factor between US gallons and liters is 3.785411784 liters per US gallon. This number is not approximate — it is the legally defined value established by the international yard and pound agreement of 1959. Using a rounded factor like 3.8 or 3.79 introduces cumulative errors that become significant when working with large quantities. For example, converting 1,000 gallons using 3.8 instead of 3.785411784 overestimates the result by about 14.6 liters — enough to matter in fuel delivery, industrial processes, or laboratory work. For cooking and everyday use, 4 decimal places (3.7854 L/gal) is typically sufficient. For scientific or commercial transactions, use the full 6-decimal factor. This converter lets you choose your precision level so you always get the accuracy you need.

Practical Applications and Common Mistakes

The most common mistake in gallon-to-liter conversion is using the US gallon factor when the source value is actually in Imperial gallons, or vice versa. This error appears frequently when comparing car fuel economy across US and UK sources — a car rated at 30 US MPG is not the same as 30 UK MPG, because the UK gallon is larger. Another common error is confusing fluid volume (gallons and liters) with weight. One gallon of water weighs 8.34 pounds (3.785 kg), but one gallon of gasoline weighs only about 6.1 pounds due to its lower density. Volume and weight are related through density and cannot be interchanged without accounting for the substance being measured. This converter handles volume conversions only — for weight conversions, the density of the specific liquid must be applied separately.

Conversion Formulas

US Gallons to Liters

Liters = US Gallons × 3.78541

Multiply the US liquid gallon value by 3.785411784 to get liters. This is the legally defined exact conversion factor.

US Gallons to Milliliters

mL = US Gallons × 3,785.41

Multiply the US gallon value by 3,785.41 to get milliliters. Useful for smaller volume measurements.

US Gallons to Imperial Gallons

UK Gallons = US Gallons × 0.832674

Multiply the US gallon value by 0.832674 to convert to Imperial (UK) gallons. The US gallon is about 83.3% the size of the Imperial gallon.

Reverse: Liters to US Gallons

US Gallons = Liters / 3.78541

Divide the liter value by 3.785411784 to convert back to US liquid gallons.

Reference Tables

Common Gallon to Liter Conversions

Pre-calculated conversions for frequently used US gallon values to liters and Imperial gallons.

US Gallons	Liters	Milliliters	Imperial Gallons
1	3.785	3,785	0.833
2	7.571	7,571	1.665
5	18.927	18,927	4.163
10	37.854	37,854	8.327
20	75.708	75,708	16.653
50	189.271	189,271	41.634
100	378.541	378,541	83.267

Common Pool and Tank Volumes

Approximate volumes of common tanks, pools, and containers in both US gallons and liters.

Container	US Gallons	Liters	Notes
Standard bathtub	40–60	151–227	Varies by tub size
10-gallon aquarium	10	37.85	Standard small fish tank
Hot tub (average)	300–500	1,136–1,893	4–6 person capacity
Above-ground pool (15ft round)	~5,000	~18,927	48" deep
55-gallon drum	55	208.20	Standard industrial drum
IBC tote	275	1,041	Intermediate bulk container

Worked Examples

Convert 5 US Gallons to Liters

A 5-gallon water jug needs to be compared to metric containers. How many liters does it hold?

Identify the formula: Liters = US Gallons × 3.785411784

Substitute the value: 5 × 3.785411784

Calculate: 5 × 3.785411784 = 18.9271 liters

5 US gallons = 18.9271 liters

Convert a 20-Gallon Fish Tank to Liters

A 20-gallon aquarium needs to be filled. How many liters of water are required?

Identify the formula: Liters = US Gallons × 3.785411784

Substitute the value: 20 × 3.785411784

Calculate: 20 × 3.785411784 = 75.7082 liters

20 US gallons = 75.7082 liters (approximately 75.7 L)

Convert 15 US Gallons to Imperial Gallons

A US fuel purchase of 15 gallons needs to be expressed in Imperial gallons for a UK report.

Identify the formula: UK Gallons = US Gallons × 0.832674

Substitute the value: 15 × 0.832674

Calculate: 15 × 0.832674 = 12.4901 Imperial gallons

15 US gallons = 12.4901 Imperial gallons

How to Use the US Gallons to Liters Converter

Choose Conversion Direction and Gallon Type

Select whether you are converting from gallons to liters or from liters to gallons using the direction toggle at the top of the input panel. Then choose your gallon type: US Liquid Gallon (the standard American gallon, 3.7854 L), Imperial UK Gallon (used in the UK and Canada, 4.5461 L), or US Dry Gallon (historic unit for dry goods, 4.4049 L). The correct gallon type is essential for accurate results — the US and Imperial gallon differ by about 20%.

Enter Your Value

Type the volume you want to convert into the input field. The converter accepts decimal values — for example, 2.5 gallons or 10.75 liters. Results update automatically as you type, so there is no need to click a button. For single-direction quick conversions, this is all you need to do. The result and the formula are displayed immediately below the input.

Review the Formula and Related Units

Below the primary result, the Formula Used section shows the exact calculation — for example, '5 × 3.785412 = 18.9271 L' — so you can verify the math and understand how the conversion works. The Related Unit Conversions section also shows the equivalent in milliliters, fluid ounces, cubic feet, quarts, and pints. Use the precision selector to control decimal places: 2 for quick estimates, 4 for standard use, or 6 for scientific precision.

Use Batch Mode, Export, or Print

For converting multiple values at once, enable Batch Mode and enter comma-separated gallon values (e.g., 1, 5, 10, 25). All results appear in a table that you can export to CSV for spreadsheet use. The Copy Result button copies the primary converted value to your clipboard. Print Results opens a print-friendly view of your conversion with all details. The Quick Reference Table at the bottom provides a handy lookup for common conversions from 0.5 to 1,000 gallons.

Frequently Asked Questions

How many liters are in a US gallon?

One US liquid gallon is exactly 3.785411784 liters. This is the legally defined conversion factor established by the international yard and pound agreement of 1959. In everyday use, it is commonly rounded to 3.785 liters or 3.79 liters. To convert any number of US gallons to liters, multiply the gallon value by 3.785411784. For example, 5 US gallons equals 5 × 3.785411784 = 18.9271 liters. To convert in the reverse direction — liters to gallons — divide the liter value by 3.785411784, or equivalently multiply by 0.2641720524. For instance, 20 liters equals 20 ÷ 3.785411784 = 5.2834 US gallons.

What is the difference between a US gallon and an Imperial gallon?

The US liquid gallon and the Imperial (UK) gallon are two separate legal definitions of the gallon, and they differ by approximately 20%. One US liquid gallon equals 3.785411784 liters, while one Imperial gallon equals 4.54609188 liters — making the Imperial gallon about 1.201 times larger. This distinction matters enormously in real-world situations. For example, a car fuel economy rating of 30 miles per UK gallon is not the same as 30 US miles per gallon — the UK figure represents better fuel efficiency because each 'gallon' of fuel is larger. Fuel prices in Canada and the UK are listed per liter, while US prices are per gallon. Always identify which gallon standard is being used before comparing volumes or prices across countries to avoid significant errors.

How do I convert liters back to gallons?

To convert liters back to US liquid gallons, divide the liter value by 3.785411784, or multiply by 0.2641720524. For example, 10 liters equals 10 ÷ 3.785411784 = 2.6417 US gallons. To convert liters to Imperial gallons, divide by 4.54609188, or multiply by 0.2199691573 — so 10 liters equals 2.1997 Imperial gallons. To convert liters to US dry gallons, divide by 4.40488377. Our converter handles all these directions automatically — simply select 'Liters to Gallons' in the conversion direction toggle, choose your gallon type, and enter the liter value. The result, formula, and related unit conversions all update instantly.

What is a US dry gallon and when is it used?

The US dry gallon is a unit of volume historically used in the United States for measuring dry commodities such as grain, berries, apples, and other agricultural products. It is defined as exactly one-eighth of a US Winchester bushel, which equals 268.8025 cubic inches or 4.40488377 liters. The US dry gallon is approximately 16.4% larger than the US liquid gallon (3.785 L) and slightly smaller than the Imperial gallon (4.546 L). In modern commerce, the US dry gallon has largely been replaced by weight measurements for dry goods and is rarely encountered in everyday use. It remains legally defined by the National Institute of Standards and Technology (NIST) and may still appear in older agricultural records, commodity contracts, or specialized industry documents.

How accurate is this converter, and what precision should I use?

This converter uses the full internationally defined conversion factors: 3.785411784 L/US liquid gallon, 4.54609188 L/Imperial gallon, and 4.40488377 L/US dry gallon. These are exact legal definitions, not approximations, so the only source of error is the precision level you choose. For cooking and household use, 2 or 4 decimal places is more than sufficient. For scientific and engineering applications where cumulative rounding errors matter, use 6 decimal places. For commercial fuel delivery or industrial fluid handling where large volumes are involved, 6 decimal places (full precision) is recommended. The difference between using 3.79 and the full factor 3.785411784 may seem small for one gallon, but at 10,000 gallons the error amounts to approximately 46 liters — meaningful in any commercial context.

Why do gas prices seem cheaper in Canada or Europe when I compare them to US prices?

The apparent price difference is partly explained by the different volume units used. In Canada, the UK, and Europe, fuel is priced per liter. In the United States, it is priced per US gallon (3.785 L). When you see fuel priced at, say, 1.60 CAD per liter in Canada, the cost per US gallon equivalent would be approximately 1.60 × 3.785 = 6.06 CAD per US gallon. Additionally, many countries include fuel taxes, currency exchange differences, and different crude oil pricing in their local fuel prices, so a direct unit-adjusted comparison still involves other economic factors. The key takeaway is that you must always convert to the same volume unit before comparing fuel prices across countries — comparing dollars-per-gallon (US) directly to dollars-per-liter (Canada or Europe) without unit conversion will always give a misleading result.