Cubic Feet Calculator
How do I calculate cubic feet?
A cubic feet calculator converts your dimensions into volume. Measure the length, width and height in feet and multiply them together: a box 10 ft long, 8 ft wide and 6 ft high holds 480 cubic feet. The calculator also shows the same volume in cubic yards, cubic metres, cubic inches, US gallons and litres, so you can order material, check a tank or compare a room in the units your supplier uses. If you measured in inches, divide the cubic inches by 1,728. If you know your price per cubic foot, enter it and the calculator gives a material cost. Leave it blank and no cost is shown. Cubic feet also decide how much concrete, gravel or soil a job needs, so if your job is a slab, use the Concrete Calculator to work out the concrete in cubic yards.
Calculate cubic feet
Enter a length greater than 0.
Enter a width greater than 0.
Enter a height greater than 0.
Enter a price of 0 or more, or leave it blank.
Enter your dimensions and click Calculate.
No result yet. Enter your dimensions and click Calculate.
Prices vary by supplier and location. Confirm with your local supplier before ordering.
The calculator covers three shapes: a rectangular box (length x width x height), a cylinder (diameter x height) and a known area (area in square feet x depth). Each dimension has its own unit selector (length, width, height and diameter: in, ft, yd, cm, m, default ft; depth: in, ft, cm, m, default in; area: sq ft, sq m, default sq ft). The box defaults to 10 x 8 x 6 ft. The cylinder defaults to 4 ft diameter and 6 ft high. The known area mode defaults to 400 sq ft x 4 in. Price per cubic foot is optional: leave it blank and no cost is shown. The formula used is shown directly under the result, so you can check the number.
What is a cubic foot?
A cubic foot is the volume of a cube 1 ft long, 1 ft wide and 1 ft high. It is the unit rooms, boxes, storage units and tanks are measured in, and the unit a cubic feet calculator works in first. Volume is length x width x height, with every dimension in feet. From square feet, volume is area x height: a floor of 400 sq ft with a depth of 4 in holds 400 x (4 / 12) = 133.33 cubic feet.
One mistake to avoid: multiplying length x width alone gives area, not volume. A 10 x 8 ft floor is 80 square feet, not 80 cubic feet. Volume needs the height as well, and without it there is no volume at all. Cubic feet measure volume and square feet measure area, so the two do not directly convert.
The conversion factors are exact, and they are stated here so you can check them: 1 cubic foot = 1,728 cubic inches (12 cubed, because there are 12 inches in a foot and three dimensions); 1 cubic yard = 27 cubic feet (3 cubed); 1 cubic foot = 7.48052 US gallons (7.48051948 exact, and 1 US gallon = 231 cubic inches); 1 cubic foot = 0.0283168 cubic metres; 1 cubic foot = 28.3168 litres; 1 cubic metre = 35.3147 cubic feet; 1 cubic foot = 6.22884 imperial gallons. Two rounded figures you may see elsewhere are not exact: Omni uses 3.281 ft per metre and The Calculator Site uses 35.31 cubic feet per cubic metre, both rounded.
When to use which unit: suppliers sell bulk material and ready-mix concrete by the cubic yard, rooms and boxes are measured in cubic feet, and metric jobs use cubic metres. A cubic yard is 27 cubic feet, so a job that sounds small in yards is large in feet: 17.78 cubic yards is 480 cubic feet.
No competitor page names an author or reviewer, except The Calculator Site (“Calculator by Alastair Hazell”). No page works one example all the way from inches through cubic feet to cubic yards and gallons, and no page covers the gallon conversion for a tank as a worked example. No page cites a standard for its conversion factors on the calculator page itself; the only citation found is on InchCalculator’s separate conversion page, which cites NIST Unit Conversion. This page shows every step of the arithmetic, so you can check the number.
Garden beds: CalculatorSoup advises adding 5 to 10 percent extra for settling and waste on a flower bed. That is a settling allowance for soil, not a standard for volume, and this calculator has no waste input because it is a pure volume tool.
How to calculate cubic feet
- Measure the length, width and height. Measure each dimension in feet. Measure a room to the finished floor and ceiling, and a box to its outside faces.
- Convert inches to feet first. If you measured in inches, divide each dimension by 12. A 144 in length is 12 ft. If you measured in yards, multiply each dimension by 3. If you measured in metres, multiply by 3.28084.
- Multiply length x width x height. For a box, multiply the three dimensions in feet. A 10 x 8 x 6 ft box holds 480 cubic feet.
- For a cylinder, use pi x radius squared x height. The radius is half the diameter. A tank 4 ft across and 6 ft high has a radius of 2 ft, so its volume is pi x 2 squared x 6 = 75.40 cubic feet.
- Divide by 27 for cubic yards. One cubic yard is 27 cubic feet. A volume of 480 cubic feet is 480 / 27 = 17.78 cubic yards.
- Multiply for gallons and litres. Multiply cubic feet by 7.48052 for US gallons and by 28.3168 for litres. A volume of 480 cubic feet holds 3,590.65 US gallons.
Conversion table: from one unit to cubic feet, and from cubic feet to the other units.
| Convert | Do this |
|---|---|
| From cubic inches | Divide by 1,728 |
| From cubic yards | Multiply by 27 |
| From cubic metres | Multiply by 35.3147 |
| From cubic centimetres | Divide by 28,316.847 |
| From US gallons | Multiply by 0.133681 |
| To cubic inches | Multiply by 1,728 |
| To cubic yards | Divide by 27 |
| To cubic metres | Multiply by 0.0283168 |
| To US gallons | Multiply by 7.48052 |
| To litres | Multiply by 28.3168 |
| To imperial gallons | Multiply by 6.22884 |
These are exact conversion factors, not rounded estimates. Displayed results are rounded to 2 decimals.
Cubic feet formula and worked example
Box: Volume (ft3) = Length x Width x Height.
Cylinder: Volume (ft3) = pi x (Diameter / 2) squared x Height.
Known area: Volume (ft3) = Area x Depth.
Volume (yd3): Volume (yd3) = Volume (ft3) / 27.
Volume (m3): Volume (m3) = Volume (ft3) x 0.0283168.
Volume (in3): Volume (in3) = Volume (ft3) x 1,728.
Volume (US gallons): Volume (US gallons) = Volume (ft3) x 7.48052.
Volume (litres): Volume (litres) = Volume (ft3) x 28.3168.
Cost: Cost = Volume (ft3) x price per cubic foot (only if a price was entered).
Worked Example
Worked example 1, box 10 x 8 x 6 ft:
Volume 10 x 8 x 6 = 480 cubic feet
480 / 27 = 17.78 cubic yards
In cubic metres, 480 x 0.0283168 = 13.59 m3
In cubic inches, 480 x 1,728 = 829,440 in3
In US gallons, 480 x 7.48052 = 3,590.65 gallons
In litres, 480 x 28.3168 = 13,592.06 litres
Worked example 2, room 12 x 10 x 8 ft:
Volume 12 x 10 x 8 = 960 cubic feet
The same room in inches: 144 x 120 x 96 = 1,658,880 cubic inches
1,658,880 / 1,728 = 960 cubic feet
Both methods agree.
Worked example 3, cylindrical tank 4 ft diameter, 6 ft high:
radius 4 / 2 = 2 ft
Volume pi x 2 squared x 6 = 75.40 cubic feet
75.40 / 27 = 2.79 cubic yards
In US gallons, 75.40 x 7.48052 = 564.02 gallons
Cubic feet calculators
Cubic Yards to Tons Calculator
Convert cubic yards to tons for bulk material.
Cubic Yards Calculator
Volume in cubic yards for slabs and beds.
Cubic Meters Calculator
Volume in cubic metres for metric jobs.
Square Yards Calculator
Area in square yards for floors and yards.
Square Meters Calculator
Area in square metres for metric jobs.
Feet and Inches Calculator
Convert between feet and inches.
Right Angle Calculator
Check a right angle with the 3-4-5 rule.
Compound Miter Calculator
Miter and bevel angles for trim and crown.
Frequently asked questions
How do I calculate cubic feet?
Multiply the length, width and height in feet: Volume = Length x Width x Height. For example, a box 10 ft long, 8 ft wide and 6 ft high holds 10 x 8 x 6 = 480 cubic feet. If you measured in inches, convert each dimension to feet first by dividing by 12, or multiply the cubic inches by 1 / 1,728. The calculator on this page does the same sum.
How do I calculate cubic feet from inches?
Work out the volume in cubic inches first, then divide by 1,728, because 1 cubic foot is 12 x 12 x 12 = 1,728 cubic inches. For example, a room 144 in long, 120 in wide and 96 in high holds 144 x 120 x 96 = 1,658,880 cubic inches, and 1,658,880 / 1,728 = 960 cubic feet. Or convert each dimension to feet first: 144 / 12 = 12 ft, 120 / 12 = 10 ft, 96 / 12 = 8 ft, and 12 x 10 x 8 = 960 cubic feet. Both methods give the same answer.
How many cubic feet are in a cubic yard?
One cubic yard is 27 cubic feet, because a yard is 3 feet and 3 x 3 x 3 = 27. To convert cubic yards to cubic feet, multiply by 27: 3 cubic yards is 81 cubic feet. To convert cubic feet to cubic yards, divide by 27: 480 cubic feet is 17.78 cubic yards. A 3 ft x 3 ft x 3 ft cube is exactly 1 cubic yard.
What is a cubic foot?
A cubic foot is the volume of a cube 1 ft long, 1 ft wide and 1 ft high. It is the unit rooms, boxes, storage units and tanks are measured in. One cubic foot equals 1,728 cubic inches, 0.0283168 cubic metres, 7.48052 US gallons and 28.3168 litres. Cubic feet measure volume, and square feet measure area, so the two do not directly convert.
How do I calculate cubic feet from yards or meters?
From yards, convert each dimension to feet first by multiplying by 3, then multiply length x width x height. Or convert the volume: cubic yards x 27 = cubic feet. From metres, convert each dimension to feet by multiplying by 3.28084, then multiply. Or convert the volume: cubic metres x 35.3147 = cubic feet. From centimetres, divide each dimension by 30.48 to get feet, or divide the cubic centimetres by 28,316.847.
How do you calculate cubic feet of concrete?
Measure the length, width and depth in feet and multiply them together. For example, a slab 10 ft long, 10 ft wide and 4 in deep is 10 x 10 x (4 / 12) = 33.33 cubic feet. Concrete is ordered in cubic yards, so divide by 27: 33.33 / 27 = 1.23 cubic yards. Add a waste allowance before you order, and use the Concrete Calculator for the bag count and cost.