Cubic Feet to Gallons Converter

Converting cubic feet to gallons turns a volume of space into the amount of liquid it holds. That is exactly what you need to size a water tank, fill a swimming pool, or estimate storage. One cubic foot to gallon conversion gives you 7.48052 US gallons. So the cubic feet to gallons formula is just your cubic feet figure times that factor. This guide shows how to convert cubic feet to gallons by hand and with our cubic feet to gallons calculator. It also covers US versus imperial gallons, water volume, a full conversion table, and real examples.

How to Convert Cubic Feet to Gallons

To convert cubic feet to gallons, multiply the volume in cubic feet by 7.480519. That is the number of US gallons inside a single cubic foot. This gallon conversion is standard across plumbing, irrigation, aquariums, and tank making. The figure comes from the unit definitions. A cubic foot equals 1,728 cubic inches. A US liquid gallon equals 231 cubic inches. Dividing 1,728 by 231 produces 7.48052 gallons per cubic foot.

The cubic feet to gallons formula looks like this:

gallons = cubic feet × 7.480519

For example, take a 12 cubic foot space. Multiply 12 by 7.480519 to get 89.77 US gallons. You can also reverse it to find how many cubic feet in a gallon. Just divide by the same factor. One gallon equals 0.1337 cubic feet. Both directions use the same constant. Once you remember 7.48052, you can move between the units either way.

People write this conversion many ways. Common forms include ft3 to gallon, cu ft to gallon, and cf to gallons. They all describe the same fluid volume relationship. You might type cubic feet to gallons converter into a search bar or do the math on paper. The answer is the same. Each abbreviation refers to the same physical link between a cubic foot and a US liquid gallon.

How Many Gallons in a Cubic Foot?

There are 7.48052 US gallons in a cubic foot. This answers the question people ask most. That question is how many gallons in a cubic foot. It is worth memorizing, since many home and trade calculations depend on it. People also ask how many gallons per cubic foot a container provides. The answer is always this same 7.48 figure for US liquid gallons.

Water is the most measured liquid. So you will often see the question framed as how many gallons in a cubic foot of water. The answer does not change. Water, oil, or any liquid in that space occupies 7.48052 gallons per cubic foot. So one cubic foot of water in gallons terms is 7.48 gallons. The question of 1 cubic foot of water equals how many gallons also resolves to 7.48 US gallons.

Knowing the gallons of water per cubic foot also helps with weight. One US gallon of water weighs about 8.34 pounds. So a single cubic foot of water weighs roughly 62.4 pounds. That matters when you load shelving, size pumps, or check if a floor can hold a full aquarium.

Cubic Feet to Gallons Conversion Table

This conversion table shows how cubic feet to gallons scales across common volumes. Each row applies the 7.480519 factor for US gallons. Use it as a quick reference for tank capacity, pool planning, and gallon conversion. You will not need the cubic feet to gallons calculator for these values.

The imperial column appears because the UK, Canada, and other countries use a larger gallon. We explain that difference below. That way you never mix the two systems.

Cubic Feet to Gallons for Specific Volumes

Many people search for an exact figure, not a formula. So here are the most requested conversions worked out in full. Each one uses the same gallons per cubic foot factor of 7.480519.

1 Cubic Foot to Gallons

The 1 cubic foot to gallons conversion equals 7.48 US gallons. This is the building block for every other answer. It also defines how many gallons in 1 cubic foot, the question behind the whole relationship.

2 Cubic Feet to Gallons

The 2 cubic feet to gallons conversion equals 14.96 US gallons. A two cubic foot bag of potting soil holds about 15 gallons of material. That helps gardeners compare soil volume to container size.

5 Cubic Feet to Gallons

The 5 cubic feet to gallons conversion equals 37.40 US gallons. It is a useful benchmark. A wheelbarrow, a mini fridge interior, or a small storage tote often falls near this size.

10 Cubic Feet to Gallons

The 10 cubic feet to gallons conversion equals 74.81 US gallons. That is roughly a compact chest freezer or a medium garden water butt.

20 Cubic Feet to Gallons

The 20 cubic feet to gallons conversion equals 149.61 US gallons. It is close to a large refrigerator or a modest rainwater barrel.

50 Cubic Feet to Gallons

The 50 cubic feet to gallons conversion equals 374.03 US gallons. That figure lines up with small backyard ponds and stock tanks.

100 Cubic Feet to Gallons

The 100 cubic feet to gallons conversion equals 748.05 US gallons. Water utilities often bill in units of 100 cubic feet, called a CCF. So this conversion turns your meter reading into gallons used.

1000 Cubic Feet to Gallons

The 1000 cubic feet to gallons conversion equals 7,480.52 US gallons. That is the scale of a large cistern, a small swimming pool, or an industrial tank.

What Is a Cubic Foot?

A cubic foot is the volume of a cube measuring one foot on every side. It equals 1,728 cubic inches, or about 28.32 liters. It is an imperial and US customary unit of volume. It works for solids, gases, and liquids alike. You measure a tank, planter box, or crate in feet. Then you multiply length by width by height. The result is the volume in cubic feet.

A cubic foot describes three-dimensional space. So it pairs naturally with liquid measurement once you know the gallon conversion. Take a box 2 feet long, 1 foot wide, and 1 foot tall. It holds 2 cubic feet. The cubic feet to gallons converter turns that into 14.96 gallons of water. Official definitions come from the National Institute of Standards and Technology. Its Office of Weights and Measures keeps US measurement consistent.

What Is a Gallon?

A gallon is a unit of fluid volume. Its exact size depends on the system you use. The US liquid gallon equals 231 cubic inches, or about 3.785 liters. It is the gallon assumed when you convert cubic feet to US gallons in American contexts. This is the gallon behind the 7.48052 factor used on this page.

The imperial gallon is used in the United Kingdom and some Commonwealth countries. It equals about 4.546 liters. That makes it roughly 20% larger than the US gallon. Because of this, one cubic foot equals only 6.2288 imperial gallons, not 7.48 US gallons. Always confirm which gallon a project uses. Mixing them produces a large error on big tanks.

US Gallons vs Imperial Gallons

The gap between the two gallon systems causes the most mistakes here. A US gallon is 3.785 liters. An imperial gallon is 4.546 liters. So the same cubic foot yields different gallon counts. For every cubic foot, you get 7.48 US gallons or 6.23 imperial gallons.

The practical rule is simple. Use US gallons for American plumbing, appliances, and fuel. Use imperial gallons for UK and Canadian measurements. If a sheet lists liters, work in metric first to avoid confusion. Our table gives both columns side by side. So you can read whichever gallon your project needs.

Cubic Feet and the 5-Gallon Bucket

A favorite real reference is the 5-gallon bucket. It is the workhorse of gardens, construction sites, and home brewing. Work backward through the gallon conversion. Divide 5 US gallons by 7.48052. The result is about 0.668 cubic feet. So a standard 5-gallon bucket holds about two-thirds of a cubic foot. That is why a 2 cubic foot bag of soil fills about three buckets.

This reverse view also answers how many cubic feet in a gallon for smaller jobs. One gallon is 0.1337 cubic feet. Multiply by five to get the bucket figure above. Keep the bucket benchmark in mind. It makes on-site volume estimates easy without a cubic feet to gallons calculator.

Real-World Examples

Consider a rectangular aquarium. It measures 4 feet long, 1.5 feet wide, and 2 feet deep. Its volume is 12 cubic feet. Converting cubic feet to gallons gives 12 times 7.480519, or 89.77 US gallons. The water volume helps you pick a filter for the right tank capacity. It also confirms the stand can bear about 748 pounds of water.

Now picture a swimming pool holding 1,500 cubic feet of water. The cubic feet of water to gallons calculation is 1,500 times 7.480519. That gives 11,221 US gallons. This swimming pool volume tells you how much chlorine to add. It also sets how long the pump runs for a full turnover.

Fuel and gas storage use the relationship too. Propane and natural gas are sold by energy content. Still, installers convert cubic feet to gallons of water equivalent when pressure-testing tanks. They lean on the same 7.48 factor for the liquid phase.

How to Convert Gallons to Cubic Feet

Sometimes you need the reverse. You turn a known gallon figure back into cubic feet. To convert gallons to cubic feet, divide the US gallons by 7.480519. You can also multiply by 0.133681. This reverse gallon conversion is useful when a tank is rated in gallons. For example, you might fit a water heater into a closet or size a rain tank against a deck.

Here are quick examples. A 40-gallon water heater takes 40 divided by 7.480519, or about 5.35 cubic feet. A 50-gallon rain barrel works out to 6.68 cubic feet. A 100-gallon stock tank equals 13.37 cubic feet. The question how many cubic feet in a gallon always resolves to 0.1337 cubic feet. So you can scale any gallon figure with one multiplication.

This also helps when products use different units. A pump rated for 600 gallons per hour moves about 80 cubic feet of water in that hour. That makes it easier to judge against a pond measured in cubic feet.

Step-by-Step Worked Method

Walking through it once makes every future conversion faster. Suppose you have a rectangular tank. It is 6 feet long, 3 feet wide, and 4 feet deep. First, find the volume in cubic feet. Multiply 6 by 3 by 4 to get 72 cubic feet. Second, apply the cubic feet to gallons formula. Multiply 72 by 7.480519 to get 538.6 US gallons. That is the whole process. It scales to any container you can measure.

What if your measurements are in inches? Divide each dimension by 12 first. Or find the volume in cubic inches and divide by 1,728. That gives cubic feet before the gallon step. Keep one consistent unit at every stage. A single mixed unit is the fastest way to miss the true tank capacity.

Round tanks use a different first step. Replace the box volume with the cylinder formula: pi times radius squared times height. Then apply the same 7.480519 factor. A cylindrical tank 5 feet across and 4 feet tall holds about 78.5 cubic feet. That is 587 US gallons. The gallon conversion attaches cleanly to any volume once the cubic feet are known.

Everyday Applications of This Conversion

This conversion appears more often than people realize. Homeowners use it to size rain barrels and cisterns. They multiply the cubic feet of a barrel by 7.48 for the gallons it captures. Aquarium keepers use it to match heaters and filters to the true water volume. Gardeners translate cubic foot bags of soil into the gallon-rated pots they fill. Pool owners convert pool dimensions into gallons to dose chemicals correctly.

Utilities lean on it as well. Many water bills measure usage in hundreds of cubic feet. Converting 100 cubic feet to gallons at 748 gallons each shows your real household use. For scale, US public water systems deliver about 39 billion gallons of water every day. HVAC and plumbing pros use the same gallons per cubic foot relationship when charging systems. The math is identical in every case. That is what makes the 7.48052 factor so valuable.

Natural Gas, Propane, and Cubic Feet

Fuel measurement adds a useful wrinkle. Natural gas is sold by the cubic foot or by the CCF, which is 100 cubic feet. Propane is sold by the liquid gallon. These are different quantities. So converting between them is not a simple volume swap. It depends on energy content, not the 7.48 liquid factor. As a rough guide, one gallon of liquid propane expands to about 36 cubic feet of vapor. That ratio comes from the fuel, not from gallon geometry.

Sometimes you still need a straight liquid volume. Then the standard cubic feet to gallons of water relationship still applies to the liquid phase. That is why technicians use it during hydrostatic testing of fuel tanks. The takeaway is simple. Use 7.480519 for water and other liquids by volume. Use fuel-specific ratios for gas and propane energy.

Water Weight and Capacity Planning

Converting cubic feet to gallons is often just the first step. The next is the weight that volume represents. One US gallon of water weighs about 8.34 pounds. So multiply your gallon figure by 8.34 to estimate load. Take a 72 cubic foot tank holding 538.6 gallons. It carries roughly 4,492 pounds of water, more than two tons. That is critical when planning a stand, a shelf, or a rooftop reservoir.

This is why the gallons of water per cubic foot figure matters beyond volume. Structural limits, pump sizing, and foundations all scale with weight. A small backyard pond at 50 cubic feet holds 374 gallons. That is about 3,120 pounds of water. The ground beneath it must be level and firm. Run the cubic feet to gallons conversion first. Then run the weight calculation. Together they show how much liquid a space holds and what it demands of its support.

Accuracy, Rounding, and Quick Estimates

For most tasks, rounding 7.480519 to 7.48 is precise enough. Many people round further to 7.5 for fast mental math. Multiplying by 7.5 overstates the result by less than 0.5%. So a 100 cubic foot estimate of 750 gallons is barely above the exact 748.05. That margin is fine for pools, soil orders, or rain barrels. Other uncertainties there are larger than the rounding.

When precision matters, keep the full 7.480519 factor. That includes scientific work, billing checks, and commercial tank certification. Carry extra decimal places through the calculation. Round only the final answer. This prevents compounding errors on large volumes. For a quick field estimate, remember that every cubic foot is about seven and a half gallons. You can size most projects in your head. Then confirm the exact figure with the cubic feet to gallons calculator above.

Converting Cubic Feet to Imperial Gallons

Readers in the UK and Canada often need the imperial result, not the US one. For them, one cubic foot equals 6.2288 imperial gallons. The formula mirrors the US version. Multiply your cubic feet by 6.2288 instead of 7.480519. So 10 cubic feet equals 62.29 imperial gallons. And 100 cubic feet equals 622.88 imperial gallons.

The difference grows with size. At 1,000 cubic feet, you get 7,480 US gallons but only 6,229 imperial gallons. That is a gap of more than 1,200 gallons. So the choice of gallon is not a small detail on large tanks. Always label your result as US or imperial. That single habit prevents costly mistakes when ordering or billing.

Tips for Accurate Measurement

Good conversions start with good measurements. Measure the inside of a container, not the outside. Wall thickness can shave real volume off a tank. Record every dimension in the same unit before you calculate. Mixed feet and inches are the top cause of errors. Round only at the final step, never in the middle.

Leave a margin for real-world fittings. Tanks have inlets, outlets, and freeboard near the top. So usable volume is often a little less than the geometric total. Treat your converted gallons as a maximum capacity. For critical jobs, confirm the figure twice. Then cross-check it against the conversion table above. A two-minute check is cheaper than a failed install.

Explore More Volume Conversions

Do you work with volume often? DigiCalc offers a full set of related tools. Start with the main volume converter for any unit pairing. Try cubic inches to gallons for smaller liquid measurements. Use liter to cubic foot when working in metric. Or use gallons to liters to bridge US and international standards. Together these cover nearly every fluid volume calculation you face.

You may also find DigiCalc's cups to liters converter useful.