Convert U.S. gal to m³ Instantly
Use this Gallons to Cubic Meters converter to change U.S. liquid gallons into cubic meters quickly and accurately. One U.S. liquid gallon equals exactly 0.003785411784 m³, or 3.785411784 liters.
Convert U.S. gallons to cubic meters, reverse m³ to gallons, calculate rectangular tank capacity, or convert one volume across gallons, liters, cubic meters, cubic feet and Imperial gallons.
Enter U.S. liquid gallons. The calculator multiplies by 0.003785411784 and also shows liters, cubic feet and Imperial gallons.
This main converter uses the U.S. liquid gallon.
Reverse the conversion from cubic meters to U.S. liquid gallons and see liters, cubic feet and Imperial gallons.
Enter inside length, width and height in feet to estimate a rectangular tank's geometric capacity.
Enter a volume and choose its starting unit to compare U.S. gallons, cubic meters, liters, cubic feet and Imperial gallons.
The Gallons to Cubic Meters conversion is a volume-unit conversion. For this page, “gallon” means the U.S. liquid gallon, which is defined as 231 cubic inches. Because the international inch is exactly 0.0254 meter, the corresponding gallon-to-cubic-meter factor is exact.
Example: 50 gal × 0.003785411784 = 0.1892705892 m³.
For quick estimating, you may see the factor shortened to 0.00378541. That is usually adequate for ordinary capacity calculations, but the calculator above retains additional precision. The physical amount of liquid does not change when you convert the unit; only the numerical expression of that volume changes.
Use this chart for common U.S. liquid gallon values. The cubic-meter column uses the full 0.003785411784 factor.
| U.S. Gallons | Cubic Meters | Liters | Cubic Feet |
|---|---|---|---|
| 0.25 gal | 0.000946353 m³ | 0.946353 L | 0.033420 ft³ |
| 0.5 gal | 0.001892706 m³ | 1.892706 L | 0.066840 ft³ |
| 1 gal | 0.003785412 m³ | 3.785412 L | 0.133681 ft³ |
| 2 gal | 0.007570824 m³ | 7.570824 L | 0.267361 ft³ |
| 5 gal | 0.018927059 m³ | 18.927059 L | 0.668403 ft³ |
| 10 gal | 0.037854118 m³ | 37.854118 L | 1.336806 ft³ |
| 25 gal | 0.094635295 m³ | 94.635295 L | 3.342014 ft³ |
| 50 gal | 0.189270589 m³ | 189.270589 L | 6.684028 ft³ |
| 100 gal | 0.378541178 m³ | 378.541178 L | 13.368056 ft³ |
| 250 gal | 0.946352946 m³ | 946.352946 L | 33.420139 ft³ |
| 500 gal | 1.892705892 m³ | 1,892.705892 L | 66.840278 ft³ |
| 1000 gal | 3.785411784 m³ | 3,785.411784 L | 133.680556 ft³ |
5 × 0.003785411784 = 0.01892705892 m³.
25 × 0.003785411784 = 0.0946352946 m³.
100 × 0.003785411784 = 0.3785411784 m³.
1,000 × 0.003785411784 = 3.785411784 m³.
One of the most important details in any gallon conversion is identifying which gallon is being used. The U.S. liquid gallon and the Imperial gallon are not the same size. If a specification simply says “gal,” look at the country, standard, equipment documentation or supplier data before converting.
For example, 100 U.S. gallons is 0.3785411784 m³, while 100 Imperial gallons is 0.454609 m³. Using the wrong gallon definition can therefore create a substantial capacity error.
The reverse conversion is useful when a metric tank, reservoir or product specification lists capacity in cubic meters but a U.S. supplier or operator works in gallons.
Equivalent shortcut: U.S. gallons ≈ cubic meters × 264.172052.
For example, 2 m³ is approximately 528.344105 U.S. gallons. The reverse calculator above performs this conversion and also displays liters, cubic feet and Imperial gallons.
The factor follows from exact unit definitions rather than an estimated physical measurement. A U.S. liquid gallon is 231 cubic inches, and one inch is exactly 0.0254 meter. Cubing the inch-to-meter relationship converts cubic inches to cubic meters. Multiplying that cubic-inch volume by 231 gives the volume of one U.S. gallon in cubic meters.
That same volume is 3.785411784 liters because 1 m³ equals 1,000 liters.
This is also why treating a gallon conversion as a simple linear length conversion would be incorrect. Volume units describe three-dimensional capacity.
Liters provide a convenient bridge between gallons and cubic meters. Because one cubic meter contains exactly 1,000 liters, you can convert U.S. gallons to liters first and then divide by 1,000.
Example: 20 gal × 3.785411784 = 75.70823568 L = 0.07570823568 m³.
This method is helpful when product labels, water-system specifications or chemical containers are already expressed in liters.
U.S. customary capacity calculations often move between gallons, cubic feet and cubic inches. One U.S. liquid gallon equals exactly 231 cubic inches and approximately 0.133680556 cubic feet. Conversely, one cubic foot contains approximately 7.48051948 U.S. gallons.
| Starting Volume | U.S. Gallons | Cubic Feet | Cubic Inches | Cubic Meters |
|---|---|---|---|---|
| 1 U.S. gal | 1 | 0.133680556 | 231 | 0.003785411784 |
| 1 ft³ | 7.48051948 | 1 | 1,728 | 0.028316846592 |
| 1 m³ | 264.172052 | 35.3146667 | 61,023.7441 | 1 |
Use the first tab for U.S. gallons to m³, the second for the reverse conversion, the tank tab for dimensions, or the multi-unit tab for broader comparisons.
Type zero or a positive decimal value. Do not add commas or unit symbols inside the input field.
Select the orange Calculate button. The result panel opens only after a valid calculation.
Read the related unit results and use the PDF button if you want a simple record of the displayed conversion.
If you know a tank's inside length, width and height instead of its stated capacity, calculate geometric volume first. The third calculator accepts dimensions in feet. It multiplies length by width by height to get cubic feet, then converts cubic feet to U.S. gallons and cubic meters.
Then: gallons ≈ ft³ × 7.48051948 and m³ = ft³ × 0.028316846592.
Real tanks can have rounded corners, domed ends, internal components, freeboard requirements or operating limits, so geometric capacity may differ from usable capacity. For purchasing, safety or process control, use the manufacturer's rated capacity where available.
The Imperial gallon is larger. Confirm the gallon standard before applying the U.S. factor.
To convert U.S. gal to m³, multiply by 0.003785411784. Divide by that factor only for m³ to gal.
1 m³ is 1,000 L, not 1 L. A gallon is about 3.785 L but only about 0.003785 m³.
Carry extra digits through intermediate calculations and round the final result according to project accuracy needs.
This conversion appears anywhere U.S. customary capacity data must be compared with metric specifications. Examples include water storage, rainwater harvesting, aquaculture, industrial tanks, irrigation, fuel storage, liquid chemicals, wastewater systems, pumps, process equipment and shipping documentation. It is also useful when a tank is sold in gallons but an engineering plan, environmental report or international datasheet uses cubic meters.
Volume conversion alone does not tell you the mass or weight of the contents. To estimate mass, you also need the material density. A gallon of water and a gallon of a denser liquid occupy the same volume but do not have the same mass.
The U.S. gallon-to-cubic-meter factor is exact from the accepted unit definitions, but your final result cannot be more reliable than the input. A tank labeled “500 gal” may be nominal, while a measured tank dimension may include uncertainty. Use precision appropriate to the source data.
For everyday estimating, displaying cubic meters to three or four decimal places can be readable. For small volumes, more decimal places are useful because one gallon is less than one hundredth of a cubic meter. The calculators retain additional digits so you can decide how much rounding is appropriate.
For authoritative SI and customary-unit information, consult the NIST Guide for SI conversion factors and the BIPM SI Brochure. These references are useful when a project requires formal unit definitions, conversion practices or SI documentation.
Continue with related tools such as the Liters to Cubic Meters converter, Liters to Cubic Yards converter, Milliliters to Liters converter, Cubic Centimeters to Cubic Inches converter, and Concrete Bags to Cubic Yards calculator. Keeping volume units consistent is especially important before combining them with density, weight, flow rate or material-cost calculations.
The same volume can be written as gallons, liters or cubic meters. The figure emphasizes the scale difference between one gallon and one full cubic meter.
Quick answers about U.S. gallons, Imperial gallons, cubic meters, liters and tank capacity conversion.