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Gallon Calculator

Convert gallons to any other unit, or find how many gallons a container holds from its size. US gallons come first, with UK and dry gallons too.

Gallon type

1 US gallon =

3.78541 liters
1 gallon 4 quarts 8 pints 16 cups = 128 fl oz
One US gallon is 4 quarts, 8 pints or 16 cups.

Water weight: 8.34 lb (3.78 kg) if it is water

1 US gallon equals

This gallon calculator works as a gallon converter and a volume tool in one. Type an amount to change gallons to liters, ounces, cups, quarts or cubic feet, or back again. You can also find how many gallons a tank holds from its size. Or find how much a gallon of water weighs.

Pick US, UK or dry gallons. Every result updates as you type.

How much is a gallon?

A gallon is a unit of volume for liquids. In the US, 1 gallon equals 231 cubic inches, or about 3.785 liters. It holds 128 fluid ounces. That is the same as 4 quarts, 8 pints or 16 cups.

The gallon is the main unit for liquids in the United States. You see it on milk jugs, gas pumps, paint cans and water heaters.

1 gallon 4 quarts 8 pints 16 cups = 128 fl oz
One US gallon is 4 quarts, 8 pints or 16 cups.

What 1 gallon equals

Use this quick list when you need one value fast:

  • 1 gallon = 3.785 liters = 3,785 milliliters (mL)
  • 1 gallon = 128 fluid ounces
  • 1 gallon = 16 cups = 8 pints = 4 quarts
  • 1 gallon = 256 tablespoons = 768 teaspoons
  • 1 gallon = 231 cubic inches = 0.134 cubic feet
  • 1/2 gallon = 64 fluid ounces = 8 cups
  • 1/4 gallon = 1 quart = 32 fluid ounces
  • 1/8 gallon = 1 pint = 16 fluid ounces = 2 cups

Types of gallons

There are three gallons, so always check which one you mean:

  • US gallon (liquid gallon). 231 cubic inches, or 3.785 liters. This is the gallon used in the United States.
  • UK gallon (imperial gallon). 4.546 liters. The UK, Canada and a few other countries used it. Today they mostly use liters, but fuel economy in the UK is still given in miles per gallon.
  • US dry gallon. 268.8 cubic inches, or 4.405 liters. It is one eighth of a bushel. People rarely use it today.

Unless a label says otherwise, a gallon in the US is the US liquid gallon. This calculator uses it by default.

Gallon conversion chart

These values are exact or rounded to 6 significant figures.

1 gallon in other units
Unit 1 US gallon 1 UK gallon 1 US dry gallon
Liters 3.78541 4.54609 4.40488
Milliliters (mL or cc) 3,785.41 4,546.09 4,404.88
US fluid ounces 128 153.722 148.947
US cups 16 19.2152 18.6184
US pints 8 9.6076 9.30918
US quarts 4 4.8038 4.65459
Tablespoons 256 307.443 297.894
Teaspoons 768 922.33 893.681
Cubic inches 231 277.419 268.803
Cubic feet 0.133681 0.160544 0.155557
Cubic meters 0.00378541 0.00454609 0.00440488
UK fluid ounces 133.228 160 155.03
UK pints 6.66139 8 7.75151

Gallons to ounces, cups and liters

Common US gallon amounts
US gallons Fluid ounces Cups Quarts Liters Action
1/8 16 2 0.5 0.47
1/4 32 4 1 0.95
1/2 64 8 2 1.89
1 128 16 4 3.79
2 256 32 8 7.57
3 384 48 12 11.36
5 640 80 20 18.93
6 768 96 24 22.71
8 1,024 128 32 30.28
10 1,280 160 40 37.85
55 7,040 880 220 208.2

Convert liters and milliliters to gallons

How many liters in a gallon?

There are 3.785 liters in a US gallon and 4.546 liters in a UK gallon. One liter is about a quarter of a US gallon.

US gallons = liters × 0.264172
Liters = US gallons × 3.78541
UK gallons = liters × 0.219969
Example: 20 litres to gallons (US) is 20 × 0.264172 = 5.28 gallons. In UK gallons, it is 20 × 0.219969 = 4.40 gallons.

Liters to gallons chart

Liters to US and UK gallons
Liters US gallons UK gallons Action
1 0.264172 0.219969
2 0.528344 0.439938
2.5 0.66043 0.549923
3.5 0.924602 0.769892
5 1.32086 1.09985
10 2.64172 2.19969
20 5.28344 4.39938
30 7.92516 6.59908
40 10.5669 8.79877
180 47.551 39.5944

So 2.5 liters is about 0.66 gallons, 3.5 liters is about 0.92 gallons, 40 liters is about 10.6 gallons and 180 L is about 47.6 gallons.

How many ml in a gallon?

There are 3,785.41 milliliters (mL) in a US gallon. A UK gallon holds 4,546.09 mL. The answer is the same for a gallon of water or any other liquid, because mL and gallons both measure volume.

mL = US gallons × 3,785.41
US gallons = mL ÷ 3,785.41
Example: A 500 mL bottle is 500 ÷ 3,785.41 = 0.132 gallons. So it takes about 7.6 bottles of 500 ml to fill a gallon.
Milliliters to US gallons
Milliliters US gallons Action
250 0.066043
355 (a soda can) 0.0937811
500 0.132086
750 0.198129
1,000 0.264172

How many cc in a gallon?

One cubic centimeter (cc or cm³) is the same as one milliliter. So there are 3,785.41 cc in a US gallon and 4,546.09 cc in a UK gallon.

Other metric units to gallons

Metric units in 1 gallon
Unit In 1 US gallon In 1 UK gallon
Centiliters (cL) 378.541 454.609
Deciliters (dL) 37.8541 45.4609
Cubic decimeters (dm³, same as liters) 3.78541 4.54609
Hectoliters (hL) 0.0378541 0.0454609
Cubic meters (m³) 0.00378541 0.00454609

One cubic meter holds 264.172 US gallons.

Convert cubic inches and cubic feet to gallons

Cubic inches per gallon

A US gallon is exactly 231 cubic inches. A UK gallon is about 277.42 cubic inches. This is the number you use when you measure a tank in inches.

US gallons = cubic inches ÷ 231
Cubic inches = US gallons × 231
Example: A box holds 1,000 cubic inches. 1,000 ÷ 231 = 4.33 gallons.

How many cubic feet are in a gallon?

One US gallon is 0.133681 cubic feet. Turn it around and 1 cubic foot holds 7.48052 US gallons, or 6.22884 UK gallons.

US gallons = cubic feet × 7.48052
Cubic feet = US gallons × 0.133681
Example: A 55-gallon drum holds 55 × 0.133681 = 7.35 cubic feet.
Cubic feet to US gallons
Cubic feet US gallons UK gallons Action
1 7.48052 6.22884
2 14.961 12.4577
5 37.4026 31.1442
10 74.8052 62.2884
50 374.026 311.442
100 748.052 622.884

Water bills often count water in CCF, or 100 cubic feet. One CCF is 748 gallons.

Cubic yards, barrels and acre-feet in gallons

Bigger units show up for concrete, oil and water supply:

Large units in US gallons
Unit US gallons UK gallons
1 cubic yard (yd³) 201.974 168.179
1 cubic meter (m³) 264.172 219.969
1 oil barrel (bbl) 42 34.9723
1 acre-foot 325,851 271,328

An oil barrel is exactly 42 US gallons. An acre-foot is the water that covers one acre one foot deep.

Convert quarts, pints and cups to gallons

4 quarts is how many gallons?

4 quarts is exactly 1 gallon. Each quart is a quarter of a gallon, which is where the name comes from.

Gallons = quarts ÷ 4
Quarts = gallons × 4
Example: 6 quarts ÷ 4 = 1.5 gallons.

Pints and gallons

A US gallon holds 8 pints. A pint is 2 cups, or 16 fluid ounces.

Gallons = pints ÷ 8
Example: 12 pints ÷ 8 = 1.5 gallons.

Gallons to cups

A US gallon holds 16 cups. Half a gallon holds 8 cups. A quarter gallon holds 4 cups.

Cups = gallons × 16
Gallons = cups ÷ 16
Example: A recipe needs 3 gallons of broth. 3 × 16 = 48 cups.

Tablespoons and teaspoons in a gallon

A US gallon holds 256 tablespoons or 768 teaspoons. Some recipes use metric spoons (15 mL tablespoon, 5 mL teaspoon). With metric spoons, a gallon is about 252 tablespoons or 757 teaspoons.

UK quarts and pints in a gallon

A UK gallon also has 4 UK quarts and 8 UK pints. Each UK unit is about 20% larger than the US unit with the same name. One US gallon equals 3.33 UK quarts or 6.66 UK pints.

Quarts, pints and cups in a gallon
Unit In 1 US gallon In 1 UK gallon
US quarts 4 4.8038
UK quarts 3.3307 4
US pints 8 9.6076
UK pints 6.66139 8
US cups 16 19.2152

Convert ounces to gallons

Ounces per gallon

There are 128 fluid ounces (fl oz) per US gallon. A UK gallon holds 160 UK fluid ounces, or about 153.7 US fluid ounces.

US fluid ounces = gallons × 128
Gallons = fluid ounces ÷ 128
Example: 1 gallon is how many ounces? 1 × 128 = 128 fl oz. A 64 oz jug is 64 ÷ 128 = half a gallon.

How many ounces in 3, 5 and 8 gallons?

Gallon to oz
US gallons US fluid ounces Action
1 128
2 256
3 384
5 640
8 1,024
10 1,280

So there are 384 ounces in 3 gallons, 640 ounces in 5 gallons and 1,024 ounces in 8 gallons.

Fluid ounces measure volume. Ounces on a scale measure weight. To change gallons to weight, see the water weight section below.

How to calculate gallons

To find how many gallons a container holds, work out its volume first. Then change that volume to gallons.

  1. Measure the inside length, width and height in inches.
  2. Multiply them to get cubic inches.
  3. Divide the cubic inches by 231 to get US gallons.

If you measured in feet, multiply the cubic feet by 7.48 instead.

Gallons in a box or rectangular tank

Gallons = length × width × height ÷ 231 (all in inches)
A tank 24 inches long, 12 inches wide and 16 inches tall holds 24 × 12 × 16 = 4,608 cubic inches. 4,608 ÷ 231 = about 19.9 gallons.

Gallons in a cylinder or round tank

Gallons = 3.1416 × radius × radius × height ÷ 231 (all in inches)
A drum 18 inches across and 36 inches tall has a radius of 9 inches. 3.1416 × 9 × 9 × 36 = about 9,161 cubic inches. 9,161 ÷ 231 = about 39.7 gallons.

Gallons from area and depth

Gallons = square feet × depth in feet × 7.48
One inch of rain on a 1,000 square foot roof is 1,000 × 1/12 × 7.48 = about 623 gallons.
For pools, use the pool volume calculator. It handles sloped floors and round, oval and kidney shapes.

Square feet into gallons

Square feet measure area, not volume. To turn square feet into gallons, you also need the depth. Multiply the area by the depth in feet, then by 7.48.

Gallons = square feet × (depth in inches ÷ 12) × 7.48
Example: 100 square feet of water 6 inches deep is 100 × 0.5 × 7.48 = 374 gallons.
10 ft6 in10 ft
100 square feet of water 6 inches deep holds about 374 gallons.
Gallons on 100 square feet
Depth US gallons
1/4 inch 15.6
1/2 inch 31.2
1 inch 62.3
6 inches 374
1 foot 748

Gallons to square feet and inches

To go from gallons to square feet, pick a depth first. One gallon spread 1 inch deep covers about 1.6 square feet. Spread 1/4 inch deep, it covers about 6.4 square feet.

Square feet = gallons × 231 ÷ (depth in inches × 144)
Depth in inches = gallons × 231 ÷ (square feet × 144)
Example: 10 gallons on a 16 square foot tray is 10 × 231 ÷ (16 × 144) = about 1 inch deep.

Paint and sealer coverage per gallon is set by the maker. Check the can for the square feet it covers.

US gallon vs UK gallon

The US and UK use different gallons. A UK gallon, also called an imperial gallon, is 4.546 liters. A US gallon is 3.785 liters.

One UK gallon equals about 1.2 US gallons. One US gallon equals about 0.83 UK gallons.

There is also a US dry gallon of 4.405 liters. It is rarely used today.

0 L 1 L 2 L 3 L 4 L 5 L US gallon 3.785 L US dry gallon 4.405 L UK gallon 4.546 L
A UK gallon holds about 20% more than a US gallon.
Gallon Liters Cubic inches US fluid ounces
US gallon 3.78541 231 128
UK gallon 4.54609 277.419 153.722
US dry gallon 4.40488 268.803 148.947

Why US and UK gallons are different

England once had several gallons for wine, ale and grain. In 1707 the wine gallon was set at 231 cubic inches. The American colonies used it, and the US kept it after independence.

In 1824 Britain replaced its old gallons with one new imperial gallon. It was the volume of 10 pounds of water at 62°F. Today the UK defines it as exactly 4.54609 liters.

The US gallon is also exact today. 231 cubic inches equals exactly 3.785411784 liters.

UK gallons to US gallons

US gallons = UK gallons × 1.20095
UK gallons = US gallons × 0.832674
Example: A UK recipe calls for 2 gallons. 2 × 1.20095 = 2.4 US gallons.

How much does a gallon of water weigh?

A US gallon of water weighs about 8.34 pounds, or 3.78 kilograms. A UK gallon of water weighs about 10 pounds, or 4.54 kilograms.

The exact weight changes a little with temperature. Water is heaviest at 39.2°F (4°C). Warm water weighs slightly less than cold water.

Use the to convert gallons to pounds, kilograms or grams.

1.00 US gal fill mark Cold: 39.2°F (4°C) 8.3454 lb Max density (1.0000) Room: 70°F (21°C) 8.3289 lb Standard (0.9980) Boiling: 212°F (100°C) 7.9958 lb Expands +4.3% (0.9584)
Water density changes with temperature. At 212°F thermal expansion causes a gallon of water to weigh 0.35 lb less than at 39.2°F.

Gallon of water weight by temperature

Weight of 1 gallon of water by temperature
Temperature Pounds per US gallon Kilograms per US gallon Pounds per UK gallon Kilograms per UK gallon
39.2°F (4°C) 8.345 3.785 10.022 4.546
60°F (15.6°C) 8.338 3.782 10.013 4.542
70°F (21°C) 8.329 3.778 10.003 4.537
100°F (37.8°C) 8.288 3.760 9.954 4.515
140°F (60°C) 8.207 3.722 9.856 4.471
212°F (100°C) 8.000 3.629 9.608 4.358

Values come from USGS water density data. Most guides round to 8.34 pounds per gallon.

Gallons to pounds and lbs to gal

Pounds = gallons × 8.34
Gallons = pounds ÷ 8.34
Example: 500 gallons to pounds is 500 × 8.34 = 4,170 pounds. 100 lbs to gal is 100 ÷ 8.34 = 12 gallons.
Gallons of water to pounds and kilograms
US gallons Pounds Kilograms
1 8.34 3.78
5 41.7 18.9
10 83.4 37.8
55 458.7 208.1
100 834 378.3
500 4,170 1,891.5
1,000 8,340 3,783

Gallon to grams and kgs to gallons

One gallon of water weighs about 3,785 grams. One kilogram of water fills about 0.264 gallons, the same as 1 liter.

Grams = gallons × 3,785
Gallons = kilograms × 0.264
Example: 10 kg of water is 10 × 0.264 = 2.64 gallons.

For other liquids, the weight depends on their density. Use the volume to weight calculator for oil, milk, gasoline and other materials.

How many tons are in a gallon?

A gallon of water weighs about 0.0042 short tons (US tons of 2,000 pounds). Turn it around: about 240 gallons of water weigh one short ton. About 264 gallons weigh one metric ton.

Where gallons are used

  • Water and tanks. Water heaters, rain barrels, aquariums and storage tanks are sold by gallons.
  • Pools and spas. Pool chemicals and pumps are sized by the pool's gallons.
  • Fuel. Gas stations in the US sell fuel by the gallon.
  • Kitchen. Milk, juice and ice cream often come in gallon or half-gallon containers.
  • Paint and cleaners. Paint, stain and many cleaning products are sold in gallon cans and jugs.

How to use the gallon calculator

The tool has three modes. Pick one at the top of the calculator.

Convert gallons

  1. Choose US, UK or US dry gallon.
  2. Type the amount.
  3. Pick the From and To units. Use the swap button to turn the conversion around.
  4. Read the result. Click any value in the "1 US gallon equals" grid to switch to that unit.

Gallons from size

  1. Choose a box, a cylinder or area and depth.
  2. Enter each size and pick its unit. You can mix inches, feet and meters.
  3. Read the gallons. Change the result unit to see liters or cubic feet.

Water weight in gallons

  1. Pick a temperature, or keep the standard 8.34 pounds per gallon.
  2. Type the amount and choose From and To units.
  3. Read the weight in pounds, kilograms or tons, or the gallons for a weight.

Each mode has a Copy button. The link in your browser keeps the mode, so you can share it.

Frequently asked questions

How many liters are in a gallon?

One US gallon is 3.785 liters. One UK gallon is 4.546 liters.

How many ounces are in a gallon?

A US gallon holds 128 US fluid ounces. A UK gallon holds 160 UK fluid ounces.

How many cups are in a gallon?

There are 16 cups in a US gallon. Half a gallon is 8 cups.

How many quarts are in a gallon?

There are 4 quarts in a gallon. Each quart is 2 pints, so a gallon is also 8 pints.

How many gallons are in a cubic foot?

One cubic foot holds about 7.48 US gallons. One gallon is about 0.134 cubic feet.

How do I calculate gallons from inches?

Multiply length × width × height in inches to get cubic inches. Divide by 231 to get US gallons.

How much does a gallon of water weigh?

About 8.34 pounds, or 3.78 kilograms.

Is a UK gallon bigger than a US gallon?

Yes. A UK gallon is about 20% larger. It holds 4.546 liters, while a US gallon holds 3.785 liters.

How many ml are in a gallon?

A US gallon holds 3,785.41 milliliters. A UK gallon holds 4,546.09 milliliters.

How many cc are in a gallon?

One cc equals one milliliter, so a US gallon holds 3,785.41 cc.

How many pints are in a gallon?

There are 8 pints in a US gallon and 8 UK pints in a UK gallon.

What is 1/8 of a gallon?

One eighth of a gallon is 1 pint, 2 cups or 16 fluid ounces.

How many gallons are in a barrel of oil?

An oil barrel holds exactly 42 US gallons, or about 159 liters.

How much do 500 gallons of water weigh?

About 4,170 pounds, or 1,891 kilograms.

Sources

We checked every value on this page against these sources.

  1. NIST Handbook 44, Appendix C: General Tables of Units of Measurement. National Institute of Standards and Technology. "US gallon, dry gallon, barrel and cubic inch values."
  2. Water Density. U.S. Geological Survey (USGS) Water Science School. "Water density and weight at each temperature."
  3. Weights and Measures Act 1985, Schedule 1. UK legislation.gov.uk. "The legal size of the UK (imperial) gallon, pint and fluid ounce."
  4. Gallon. Encyclopaedia Britannica. "History of the wine gallon and the imperial gallon."

Reviewed by the VolumeCalculator.dev team. Last reviewed: October 30, 2026. How we check our numbers