Short answer
- One US gallon is exactly 3.785411784 liters, and one imperial gallon is exactly 4.54609 liters. Going the other way, 1 liter is 0.264172 US gallons or 0.219969 imperial gallons. To convert liters to US gallons, divide the number of liters by 3.785411784, or multiply by 0.264172. To convert liters to imperial gallons, divide by 4.54609, or multiply by 0.219969. To convert gallons back to liters, multiply US gallons by 3.785411784 or imperial gallons by 4.54609. Every figure in this article is computed from those two exact constants, and the only decision you have to make before calculating is which gallon your source, label, or recipe is using. In the United States, that is the US gallon. In older British and Commonwealth material, it may be the imperial gallon.
By Emma Hudson
Converting liters to gallons looks like a one line calculation, and it is, once you know which gallon you mean. The United States and the imperial system used in the United Kingdom define the gallon differently, by about a fifth, so a single liters to gallons figure quoted without that detail can be wrong by enough to matter for a fuel tank, a fish tank, or a large recipe. This guide gives both answers, the formulas in both directions, full conversion tables, and worked examples, so you can convert with confidence and check anyone else’s figure.
The Two Gallons at a Glance
| Unit | Liters per gallon | Gallons per liter | Fluid ounces per gallon |
|---|---|---|---|
| US gallon | 3.785411784 | 0.264172 | 128 US fluid ounces |
| Imperial gallon | 4.54609 | 0.219969 | 160 imperial fluid ounces |
The imperial gallon is the larger of the two. It holds 0.760678 more liters than a US gallon, which is about 20 percent more. Put the other way round, one imperial gallon equals 1.200950 US gallons, and one US gallon equals 0.832674 imperial gallons. The fluid ounce rows carry a second trap for anyone converting through ounces: the imperial gallon contains more fluid ounces, but each imperial fluid ounce is slightly smaller, at 28.413 milliliters against 29.574 milliliters for a US fluid ounce. Both systems agree on the internal structure, though: in each system a gallon is 4 quarts, a quart is 2 pints, and a pint is 2 cups in US measure.
How to Convert Liters to Gallons
The method is a single division. Take the number of liters and divide it by the liters per gallon figure for the system you want. For US gallons, divide by 3.785411784. For imperial gallons, divide by 4.54609. If you prefer to multiply, use the gallons per liter factors instead: multiply liters by 0.264172 for US gallons or by 0.219969 for imperial gallons. Both routes give the same answer, because each pair of factors are reciprocals of each other.
Worked examples, liters to US gallons:
- 1 liter divided by 3.785411784 equals 0.264172 US gallons.
- 3 liters divided by 3.785411784 equals 0.792516 US gallons.
- 7 liters divided by 3.785411784 equals 1.849204 US gallons, so 7l to gallons is about 1.85 US gallons.
- 10 liters divided by 3.785411784 equals 2.641721 US gallons.
- 20 liters divided by 3.785411784 equals 5.283441 US gallons.
Worked examples, liters to imperial gallons:
- 1 liter divided by 4.54609 equals 0.219969 imperial gallons.
- 3 liters divided by 4.54609 equals 0.659908 imperial gallons.
- 10 liters divided by 4.54609 equals 2.199692 imperial gallons.
- 20 liters divided by 4.54609 equals 4.399385 imperial gallons.
So the common question, how many gallons is 3 liters, has two correct answers: 0.792516 US gallons or 0.659908 imperial gallons. Neither answer is complete unless it names its gallon.
Liters to Gallons Conversion Table
Each row below is computed from the two exact constants and rounded to six decimal places for display.
| Liters | US gallons | Imperial gallons |
|---|---|---|
| 1 | 0.264172 | 0.219969 |
| 2 | 0.528344 | 0.439938 |
| 3 | 0.792516 | 0.659908 |
| 4 | 1.056688 | 0.879877 |
| 5 | 1.320860 | 1.099846 |
| 6 | 1.585032 | 1.319815 |
| 7 | 1.849204 | 1.539785 |
| 8 | 2.113376 | 1.759754 |
| 9 | 2.377548 | 1.979723 |
| 10 | 2.641721 | 2.199692 |
| 15 | 3.962581 | 3.299539 |
| 20 | 5.283441 | 4.399385 |
| 25 | 6.604301 | 5.499231 |
| 30 | 7.925162 | 6.599077 |
| 40 | 10.566882 | 8.798770 |
| 50 | 13.208603 | 10.998462 |
| 75 | 19.812904 | 16.497694 |
| 100 | 26.417205 | 21.996925 |
| 200 | 52.834410 | 43.993850 |
| 500 | 132.086026 | 109.984624 |
| 1000 | 264.172052 | 219.969248 |
Because every row scales from the same constants, the table is internally consistent: doubling the liters doubles the gallons in both columns, and the imperial column is always the US column multiplied by 0.832674.
How to Convert Gallons to Liters
The reverse conversion is a single multiplication. Multiply US gallons by 3.785411784 to get liters, or multiply imperial gallons by 4.54609. This is the direction you need when a US specification, such as a tank size, a water heater capacity, or a fuel economy figure, has to be expressed for a reader who works in liters.
Worked examples:
- 1 US gallon times 3.785411784 equals 3.78541 liters.
- 2 US gallons times 3.785411784 equals 7.57082 liters.
- 5 US gallons times 3.785411784 equals 18.92706 liters.
- 10 US gallons times 3.785411784 equals 37.85412 liters.
- 1 imperial gallon times 4.54609 equals 4.54609 liters.
- 5 imperial gallons times 4.54609 equals 22.73045 liters.
- 10 imperial gallons times 4.54609 equals 45.46090 liters.
The phrase gallons in to litres, which many people type into a search engine, is simply this reverse direction. It uses the same constants and the same multiplication, not a different formula.
Gallons to Liters Conversion Table
| Gallons | Liters (US gallons) | Liters (imperial gallons) |
|---|---|---|
| 1 | 3.78541 | 4.54609 |
| 2 | 7.57082 | 9.09218 |
| 3 | 11.35624 | 13.63827 |
| 4 | 15.14165 | 18.18436 |
| 5 | 18.92706 | 22.73045 |
| 6 | 22.71247 | 27.27654 |
| 7 | 26.49788 | 31.82263 |
| 8 | 30.28329 | 36.36872 |
| 9 | 34.06871 | 40.91481 |
| 10 | 37.85412 | 45.46090 |
| 15 | 56.78118 | 68.19135 |
| 20 | 75.70824 | 90.92180 |
| 25 | 94.63529 | 113.65225 |
| 50 | 189.27059 | 227.30450 |
| 100 | 378.54118 | 454.60900 |
Fractions of a gallon come up constantly in kitchens and workshops. A quarter of a US gallon is 0.94635 liters, a half gallon is 1.89271 liters, and three quarters is 2.83906 liters. In imperial measure the same fractions are 1.13652, 2.27305, and 3.40957 liters. A US half gallon carton of milk, at 1.89271 liters, is noticeably less than a 2 liter bottle, and the table above shows why: a full US gallon is well short of 4 liters.
Why There Are Two Gallons
Britain once used several different gallons at the same time, including a wine gallon, an ale gallon, and a corn gallon for dry goods. The American colonies used the wine gallon, and the United States kept it after independence. That gallon is defined as 231 cubic inches. Britain swept its older gallons away in 1824 and replaced them with a single imperial gallon, based on the volume of 10 pounds of water under set conditions. The two systems have measured different volumes ever since.
The modern values are exact by definition, not measurements that might be revised. Since 1959 the inch has been defined internationally as exactly 2.54 centimeters. A US gallon of 231 cubic inches therefore works out to exactly 3.785411784 liters, because a liter is exactly one cubic decimeter, a cube 10 centimeters on each side. The imperial gallon is defined in United Kingdom law as exactly 4.54609 liters. Neither figure is an approximation, and any conversion table that disagrees with them in the early decimal places is using a rounded or wrong constant. A third gallon, the US dry gallon, exists in law for dry measures such as grains and produce, but it is not used for liquids and plays no part in fuel, recipe, or tank conversions.
Fuel: Gallons, Liters, and Miles per Gallon
Fuel is where the two gallons cause the most expensive confusion, and it is also where a second distinction matters. Miles per gallon and liters per 100 kilometers are not the same kind of measure. Miles per gallon is a distance per unit of fuel, so a higher number is better. Liters per 100 kilometers is a fuel use per fixed distance, so a lower number is better. Because they are reciprocals of each other, you cannot convert between them by multiplying by the gallon factor. The National Institute of Standards and Technology gives the conversion directly: to turn miles per US gallon into liters per 100 kilometers, divide 235.215 by the miles per gallon figure.
A car rated at 30 miles per US gallon therefore uses 235.215 divided by 30, which is 7.840 liters per 100 kilometers. A car using 8 liters per 100 kilometers converts back to 235.215 divided by 8, which is 29.402 miles per US gallon. The same reciprocal method works for imperial miles per gallon with a different constant, 282.481, because the imperial gallon is larger. A British car rated at 40 miles per imperial gallon uses 282.481 divided by 40, which is 7.062 liters per 100 kilometers. Expressed in US gallons, that same car scores only 33.3 miles per gallon. Nothing about the car changed: the British figure looks about a fifth better purely because the imperial gallon contains about a fifth more fuel. Comparing a US and a UK fuel economy figure without converting the gallon first is comparing two different quantities.
Tank sizes need the plain volume conversion instead. A fuel tank listed as 55 liters holds 55 divided by 3.785411784, which is 14.529 US gallons, or 12.098 imperial gallons. Filling a 12 US gallon tank means buying 45.425 liters at a metric priced pump. And a driver comparing fuel prices across a border can price a full gallon either way: one US gallon of fuel costs 3.785411784 times the price per liter, and one imperial gallon costs 4.54609 times the price per liter.
Worked Example: An Aquarium
Aquarium products are sold internationally, so tank volumes in liters and dosing instructions in gallons often appear on the same label. Take a tank sold as 75 liters. In US gallons that is 75 divided by 3.785411784, which is 19.813 gallons. In imperial gallons it is 75 divided by 4.54609, which is 16.498 gallons. The tank is the same either way; only the number changes.
Now suppose a water treatment label says to add 5 milliliters of product for every 10 US gallons. For this tank the correct dose is based on 19.813 gallons, so roughly 9.9 milliliters. If you mistakenly read the imperial figure as US gallons and dosed for 16.498 gallons, you would add about 8.2 milliliters, roughly 17 percent too little. Run the error the other way, treating a US gallon figure as imperial, and you would overdose by a similar margin. The safe habit with any per gallon instruction is to check which gallon the manufacturer means, which is usually the system of the country where the product is sold, before measuring anything.
Smaller tanks scale the same way. A 20 liter starter tank is 5.283 US gallons, a 40 liter tank is 10.567 US gallons, and a 200 liter tank is 52.834 US gallons. Stocking guides, filter ratings, and heater sizes quoted per gallon all need the same check.
Worked Example: A Recipe
Recipes cross the Atlantic in both directions, and large batch recipes, brewing, and preserving are where gallons appear in a kitchen. Suppose a soup recipe written for a metric kitchen calls for 2 liters of stock. In US measure that is 0.5283 US gallons. Few cooks measure in fractions of a gallon, so keep converting down the chain: 2 liters is 2.113 US quarts, 8.454 US cups, or 67.628 US fluid ounces. The cross check works because the chain is consistent: 1 US gallon is 4 quarts, 16 cups, or 128 fluid ounces, and 1 US cup is 236.588 milliliters.
Run the same recipe the other way. A US recipe calling for 1 gallon of stock needs 3.78541 liters, and a half gallon needs 1.89271 liters. A recipe calling for 5 gallons of water for a large preserving batch needs 18.92706 liters. One caution belongs here: the US cup of 236.588 milliliters is a defined unit, while the mugs and cups in a kitchen drawer are not, so for anything where proportion matters, measure in milliliters or fluid ounces rather than by mugful.
Everyday Volumes in Both Units
A few familiar containers show the conversion at household scale. A 500 milliliter water bottle is 0.132 US gallons, about an eighth of a gallon. A 2 liter soda bottle is 0.528 US gallons, just over half a gallon. A 5 US gallon water cooler bottle holds 18.927 liters, which is why the similar bottles sold in metric countries are usually labeled 19 liters: 19 liters is 5.019 US gallons. A standard oil barrel in the petroleum trade is 42 US gallons, which is 158.987 liters. At the top of the household scale, 1000 liters, a cubic meter of water, is 264.172 US gallons.
Related Conversions
Liters and gallons sit in the middle of a chain of volume units, and the same two constants unlock all of it. One liter is exactly 1000 milliliters. One US gallon is 128 US fluid ounces, 16 US cups, 8 US pints, or 4 US quarts. One imperial gallon is 160 imperial fluid ounces, 8 imperial pints, or 4 imperial quarts. In metric terms, a US fluid ounce is 29.574 milliliters, an imperial fluid ounce is 28.413 milliliters, a US pint is 473.176 milliliters, an imperial pint is 568.261 milliliters, a US quart is 946.353 milliliters, and an imperial quart is 1136.523 milliliters.
Two patterns are worth noticing. First, the imperial system’s pint and quart are each about a fifth larger than the US versions, matching the gallon difference, because each system builds its gallon from its own smaller units. Second, the imperial fluid ounce breaks the pattern and is slightly smaller than the US fluid ounce, because the imperial gallon is divided into 160 ounces against the US gallon’s 128. Anyone converting a drinks recipe or a chemical dilution through ounces needs that detail, because converting gallons correctly and ounces incorrectly still gives a wrong answer.
Precision and Rounding
For cooking, cleaning, and most household tasks, a rounded constant is fine. Using 3.79 liters per US gallon instead of the exact figure overstates each gallon by about 4.6 milliliters, less than a teaspoon, which no recipe will notice. Using 3.785 understates each gallon by about 0.41 milliliters. The rounding only starts to matter when the volumes grow: at 100 gallons the 3.785 shortcut is short by about 41 milliliters, and at 1000 gallons the 3.79 shortcut is over by about 4.6 liters. Fuel depots, breweries, and laboratories therefore work with the full constants.
Two working rules keep conversions accurate at any scale. First, carry the full constant through every step of a multi step conversion and round only the final answer; rounding at each step stacks small errors in the same direction. Second, match the precision of the answer to the precision of the starting figure. A tank described as about 50 liters converts honestly to about 13.2 US gallons, and writing 13.208603 would claim a precision the original figure never had. The tables in this article keep six decimal places so that readers can round to whatever their task needs.
Common Mistakes
The first and largest mistake is using the wrong gallon, which puts the answer out by about 20 percent in either direction. The second is treating miles per gallon as if it were a volume and converting it with the gallon factor; fuel economy needs the reciprocal method described above, with 235.215 for US gallons or 282.481 for imperial gallons. The third is rounding the constant before calculating, then multiplying by a large volume, which turns a harmless shortcut into a real error. The fourth is assuming that units with the same name are the same size across systems: the fluid ounce, pint, and quart all differ between US and imperial measure, as the related conversions section shows. The fifth is applying a liquid conversion to the US dry gallon, a separate legal unit for dry goods that should never be used for fuel, water, or recipes.
Spelling: Liters and Litres
Liters is the US spelling and litres is the spelling used in Britain and most of the Commonwealth. They are exactly the same unit, and 1 litre to gallon conversions use the identical numbers as 1 liter to gallon conversions. The spelling is still a useful clue about which gallon a writer probably means: a page that spells the unit litres is more likely to be working in imperial gallons, and a page that spells it liters is more likely to mean US gallons. Treat the spelling as a prompt to check, never as proof, and verify the figure itself against the constants: 3.785411784 for US gallons, 4.54609 for imperial gallons.
Frequently Asked Questions
How many liters for gallon?
For 1 US gallon, 3.785411784 liters. For 1 imperial gallon, 4.54609 liters. The shorter figure of 3.78541 liters per US gallon, used in many tables, is the same exact value rounded to five decimal places.
How many liters is a gallon?
The same answer, because the question is the same conversion: 3.785411784 liters in a US gallon or 4.54609 liters in an imperial gallon. Which answer applies depends on the country and system behind the gallon being quoted.
1 gallon is how many liters?
1 gallon is 3.785411784 liters if it is a US gallon, and 4.54609 liters if it is an imperial gallon. If a US source says a gallon without qualification, it means the US gallon.
How many gallons is 3 liters?
3 liters is 0.792516 US gallons or 0.659908 imperial gallons. In kitchen terms, 3 liters is a little under four fifths of a US gallon.
What is 7l to gallons?
7 liters is 1.849204 US gallons or 1.539785 imperial gallons. Rounded for everyday use, that is about 1.85 US gallons.
What is 1 litre to gallon?
1 liter, spelled litre in British English, is 0.264172 US gallons or 0.219969 imperial gallons. The spelling does not change the unit or the arithmetic.
How do I convert gallons to liters?
Multiply by the liters per gallon constant. US gallons times 3.785411784 gives liters, and imperial gallons times 4.54609 gives liters. For example, 5 US gallons is 18.92706 liters.
How do I convert liters to gallons?
Divide by the same constants, or multiply by their reciprocals. Liters divided by 3.785411784, or times 0.264172, gives US gallons. Liters divided by 4.54609, or times 0.219969, gives imperial gallons.
Is a UK gallon bigger than a US gallon?
Yes. The imperial gallon used in the United Kingdom is 4.54609 liters against 3.785411784 liters for the US gallon, so it is about 20 percent larger, a difference of 0.760678 liters per gallon.
How many liters are in 5 gallons?
5 US gallons is 18.92706 liters, and 5 imperial gallons is 22.73045 liters. The difference between the two answers is more than 3.8 liters, which is itself more than a US gallon.
How many gallons is 100 liters?
100 liters is 26.417205 US gallons or 21.996925 imperial gallons. A 100 liter tank is therefore roughly a 26 gallon tank in US terms.
Why do some sources say 3.785 and others say 3.78541?
They are the same figure at different precisions. The exact value is 3.785411784 liters per US gallon. 3.78541 is that value rounded to five decimal places and 3.785 to three. The gap between 3.785 and the exact value is about 0.41 milliliters per gallon, negligible at household scale and worth correcting at industrial scale.
Keep reading: How Many Ounces in a Gallon
Keep reading: How Many Cups in a Gallon? 16 US Cups, Explained
Keep reading: Liters to Ounces: Exact Conversion Table & Examples
Keep reading: Milliliters in a Gallon
Sources & references
- National Institute of Standards and Technology, NIST Guide to the SI (SP 811), Appendix B.9, Factors for units listed by kind of quantity or field of science. Used for the gallon conversion factors (gallon (U.S.) to liter, 3.785 412, the rounded display of the exact value 3.785411784; gallon [Canadian and U.K. (Imperial)] to liter, 4.546 09, marked exact), the liter as exactly 1.0 E-03 cubic meters, and the US cup, fluid ounce, pint, and quart factors. https://www.nist.gov/physical-measurement-laboratory/nist-guide-si-appendix-b9
- National Institute of Standards and Technology, NIST Guide to the SI (SP 811), Appendix B, Conversion Factors, section B.5. Used for the motor vehicle fuel conversion: divide 235.215 by miles per US gallon to get liters per 100 kilometers, and for the point that miles per gallon and liters per 100 kilometers are reciprocal measures. Section B.6 was used for the 1959 definition of the yard and foot, from which the exact inch of 2.54 centimeters follows. https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors
- The Units of Measurement Regulations 1995 (UK Statutory Instrument 1995 No. 1804), Schedule. Used for the legal metric equivalents of imperial units: gallon 4.54609 litres, fluid ounce 28.4130625 millilitres, pint 0.56826125 litre, and quart 1.1365225 litres. http://www.legislation.gov.uk/uksi/1995/1804/schedules/made
- National Institute of Standards and Technology, Approximate Conversions from Metric to U.S. Customary Measures (NIST SP 365, Metric Conversion Card). Used as a cross check for the approximate liter to gallon factor of 0.26 and the pint and quart approximations. https://www.nist.gov/pml/owm/metric-si/unit-conversion/approximate-conversions-metric-us-customary-measures
