What is the formula for gallons to cubic meters?

m³ = imperial gallons × 0.00454609, or m³ = US gallons × 0.003785411784. Both come from the litre, which is this converter's base unit for volume: a cubic metre is exactly 1,000 litres, so a gallon in litres divided by 1,000 is the same gallon in cubic metres. Reversed, one cubic metre is 219.969248299 imperial gallons or 264.172052358 US gallons.

Worked example: what is 100 gallons in cubic meters?

100 imperial gallons is 0.454609 m³ and 100 US gallons is 0.3785411784 m³. The factor only moves the decimal point, so the rest follows: 5 imperial gallons is 0.02273045 m³, 50 is 0.2273045 m³, 500 is 2.273045 m³ and 1,000 is 4.54609 m³. In US gallons, 1,000 is 3.785411784 m³.

Which gallon is my figure in?

It follows where the number came from, not the word itself. A US pump, milk jug or paint tin means the US liquid gallon of 3.785411784 litres. A tank, pump or rainwater figure quoted in the UK or Ireland, or in older Canadian and Australian documents, is usually the imperial gallon of 4.54609 litres. This page starts on the imperial gallon and keeps the US gallon one pick away in the same From menu, and the list under the answer shows the US gallon row while you read, so one imperial gallon is visibly 1.2009499255 US gallons.

How do I convert cubic meters back to gallons?

Press the swap button between the two boxes and the page runs cubic metres into imperial gallons: 1 m³ is 219.969248299 gallons, 0.5 m³ is 109.98462415 gallons and 10 m³ is 2,199.69248299 gallons. The same cubic metre is 264.172052358 US gallons once you pick Gallon (US) in the To menu. Swap keeps the number you typed rather than the answer, so it converts that figure in the new direction.

Is a cubic metre the same as 1,000 litres?

Yes, exactly, and the converter is built that way: the litre is the base unit for volume here and the cubic metre carries a factor of exactly 1,000. So 1 m³ is 1,000 L, 1 L is 0.001 m³, and an imperial gallon of 4.54609 L becomes 0.00454609 m³ with the decimal point moved three places. A US gallon of 3.785411784 L becomes 0.003785411784 m³ the same way.

Why did a small number come back as 4.54609e-7?

Because anything below 0.000001 is printed in exponential notation rather than as a row of leading zeros. 0.0001 imperial gallons is 4.54609e-7 m³, while 0.1 gallons stays decimal at 0.000454609 m³. At that size the friendlier rows are already in the list underneath: 0.1 imperial gallons is 0.454609 L and 454.609 mL.

Does it know the US dry gallon?

No. The volume menu holds one US gallon, the liquid one of 231 cubic inches, next to the imperial gallon, US teaspoons, tablespoons, fluid ounces, cups, pints and quarts, the millilitre and litre, the cubic metre, the cubic inch and the cubic foot. The US dry gallon is not in the table, so a dry measure needs converting elsewhere rather than assuming this one fits.

Is anything I type uploaded?

No. Every factor ships with the page and the arithmetic runs in your browser, with no account and nothing sent anywhere, so it keeps working with no network connection once the page has loaded.

Gallons to Cubic Meters (gal to m³)

Gallons to cubic metres depends on which gallon you have, and both sizes are exact by definition rather than measured: the imperial gallon is exactly 4.54609 litres, so 0.00454609 m³, and the US liquid gallon is 231 cubic inches, which is exactly 3.785411784 litres, so 0.003785411784 m³. The imperial gallon is the larger by about a fifth, since 1 imperial gallon is 1.2009499255 US gallons and 1 US gallon is 0.832674184629 imperial gallons. This page opens the converter with Gallon (imperial) in the From box and Cubic metre in the To box, ahead of whatever pair you last used, so 1 gallon reads 0.00454609 m³, 100 gallons reads 0.454609 m³ and 1,000 gallons reads 4.54609 m³, while picking Gallon (US) in the same menu switches to the American one, where 100 gallons is 0.3785411784 m³ and 1,000 gallons is 3.785411784 m³. Under the answer the same volume is listed in millilitres, litres, cubic metres and the US kitchen units at once, so one imperial gallon shows as 4,546.09 mL, 4.54609 L and 1.2009499255 US gallons, and the Show 5 more switch adds the imperial fluid ounce, the imperial pint, the cubic inch and the cubic foot: 160 imperial fluid ounces, 8 imperial pints, 277.419432792 in³ and 0.160543653236 ft³.

From

To0.00454609

1 gal in every volume unit

MillilitremL
4,546.09
LitreL
4.54609
Cubic metrem³
0.00454609
Teaspoon (US)tsp
922.329542788
Tablespoon (US)tbsp
307.443180929
Fluid ounce (US)fl oz
153.721590465
Cup (US)cup
19.2151988081
Pint (US)pt
9.60759940404
Quart (US)qt
4.80379970202
Gallon (US)gal
1.2009499255

Common questions

How many cubic meters are in a gallon?: 0.00454609 m³ for an imperial gallon and 0.003785411784 m³ for a US liquid gallon, and the page carries both. The imperial gallon is about 20 percent larger: 1 imperial gallon is 1.2009499255 US gallons and 1 US gallon is 0.832674184629 imperial gallons. Neither factor is an estimate, because the imperial gallon is defined as exactly 4.54609 litres and the US liquid gallon as exactly 231 cubic inches.
What is the formula for gallons to cubic meters?: m³ = imperial gallons × 0.00454609, or m³ = US gallons × 0.003785411784. Both come from the litre, which is this converter's base unit for volume: a cubic metre is exactly 1,000 litres, so a gallon in litres divided by 1,000 is the same gallon in cubic metres. Reversed, one cubic metre is 219.969248299 imperial gallons or 264.172052358 US gallons.
Worked example: what is 100 gallons in cubic meters?: 100 imperial gallons is 0.454609 m³ and 100 US gallons is 0.3785411784 m³. The factor only moves the decimal point, so the rest follows: 5 imperial gallons is 0.02273045 m³, 50 is 0.2273045 m³, 500 is 2.273045 m³ and 1,000 is 4.54609 m³. In US gallons, 1,000 is 3.785411784 m³.
Which gallon is my figure in?: It follows where the number came from, not the word itself. A US pump, milk jug or paint tin means the US liquid gallon of 3.785411784 litres. A tank, pump or rainwater figure quoted in the UK or Ireland, or in older Canadian and Australian documents, is usually the imperial gallon of 4.54609 litres. This page starts on the imperial gallon and keeps the US gallon one pick away in the same From menu, and the list under the answer shows the US gallon row while you read, so one imperial gallon is visibly 1.2009499255 US gallons.
How do I convert cubic meters back to gallons?: Press the swap button between the two boxes and the page runs cubic metres into imperial gallons: 1 m³ is 219.969248299 gallons, 0.5 m³ is 109.98462415 gallons and 10 m³ is 2,199.69248299 gallons. The same cubic metre is 264.172052358 US gallons once you pick Gallon (US) in the To menu. Swap keeps the number you typed rather than the answer, so it converts that figure in the new direction.
Is a cubic metre the same as 1,000 litres?: Yes, exactly, and the converter is built that way: the litre is the base unit for volume here and the cubic metre carries a factor of exactly 1,000. So 1 m³ is 1,000 L, 1 L is 0.001 m³, and an imperial gallon of 4.54609 L becomes 0.00454609 m³ with the decimal point moved three places. A US gallon of 3.785411784 L becomes 0.003785411784 m³ the same way.
Why did a small number come back as 4.54609e-7?: Because anything below 0.000001 is printed in exponential notation rather than as a row of leading zeros. 0.0001 imperial gallons is 4.54609e-7 m³, while 0.1 gallons stays decimal at 0.000454609 m³. At that size the friendlier rows are already in the list underneath: 0.1 imperial gallons is 0.454609 L and 454.609 mL.
Does it know the US dry gallon?: No. The volume menu holds one US gallon, the liquid one of 231 cubic inches, next to the imperial gallon, US teaspoons, tablespoons, fluid ounces, cups, pints and quarts, the millilitre and litre, the cubic metre, the cubic inch and the cubic foot. The US dry gallon is not in the table, so a dry measure needs converting elsewhere rather than assuming this one fits.
Is anything I type uploaded?: No. Every factor ships with the page and the arithmetic runs in your browser, with no account and nothing sent anywhere, so it keeps working with no network connection once the page has loaded.

Conversion factors are the exact legal definitions where one exists. An inch is exactly 2.54 cm and a pound exactly 0.45359237 kg, so those conversions are exact rather than approximate. Temperature uses offsets rather than factors, and that is shown in the working.