Cubic Footage Calculator
Cubic footage sounds like one calculation, but in practice it arrives three different ways: a crate you measured on all three sides, a round tank you measured across, or a room or garden bed where you know the floor area and only need to add a depth. Most tools force all three jobs through a single box form, and the conversions afterward are left to you.
This calculator gives each job its own mode. Enter a box, a cylinder by its diameter, or a floor area times a height, in feet, inches, yards, meters, or centimeters, and it returns the volume in cubic feet with conversions to cubic inches, cubic yards, cubic meters, liters, and US gallons, the surface area where the shape defines one, and the working shown step by step.
Result
Result
Result
Box and cylinder results include the total surface area of the closed shape. The floor area mode reports volume only, because an area alone does not define a shape whose surface could be measured. Volumes assume the full geometric shape.
Quick Answer
- Quick Answer
- How to use the cubic footage calculator
- The formulas behind the three modes
- Worked examples, one per mode
- Measuring in inches: divide by 1,728, or let the unit selector work
- From cubic feet to a bulk order: coverage by depth
- What most cubic footage calculators miss
- Frequently Asked Questions
- Add This Calculator to Your Website
- References
How to use the cubic footage calculator
Box if you have three sides, Cylinder if you measured across a round end, Floor area if a listing or plan already gives you square feet.
In the box and cylinder modes a single unit applies to every measurement in that mode: feet, inches, yards, meters, or centimeters. Mixed units in one mode are not supported, so convert the odd one first.
The steps show each side converted to feet and the multiplication itself, so a wrong unit or a diameter entered where a radius belongs shows up before you order anything.
Cubic yards for bulk landscaping and concrete, gallons for tanks and pools, liters and cubic meters for metric specifications, cubic inches for carrier paperwork.
If the job is a single box and you want a deeper treatment of that one case, the box volume calculator goes further on carton and crate volumes. If all your measurements are already in feet and your shape is a sphere, which this calculator does not offer, the cu feet calculator covers box, cylinder, and sphere in feet only.
The formulas behind the three modes
For a rectangular box, cubic footage is length times width times height, all in the same unit. For a cylinder, the formula uses the radius, which is half the diameter: V = pi x r² x h. And when you already know the floor area in square feet, volume is simply area times height. The calculator converts every input to feet first, using the exact factors in NIST guidance on conversion factors: an inch is 1/12 of a foot, a yard is 3 feet, a meter is 3.28084 feet, and a centimeter is 0.0328084 feet.
Worked examples, one per mode
Each mode is pre-filled with its example, so every row below reproduces exactly with one click.
| Mode and inputs | Cubic feet | Cubic yards | Liters | US gallons | Surface area |
|---|---|---|---|---|---|
| Box, 3 x 4 x 5 ft | 60.00 ft³ | 2.222 yd³ | 1699.01 L | 448.83 gal | 94.00 ft² |
| Cylinder, diameter 4 ft, height 10 ft | 125.66 ft³ | 4.654 yd³ | 3558.39 L | 940.03 gal | 150.80 ft² |
| Floor area, 50 ft² x 0.5 ft | 25.00 ft³ | 0.926 yd³ | 707.92 L | 187.01 gal | Not applicable |
The cylinder row is worth a second look. Its surface area, 150.80 ft², counts the curved wall plus both circular ends, because the formula is 2 pi r² + 2 pi r h. For an open-top tank, subtract one end cap (pi r², here 12.57 ft²) before ordering liner or coating. The floor area row honestly reports no surface area: 50 square feet could be a 5 by 10 ft rectangle or an L-shaped room, and each would need a different wall area, so the tool refuses to invent one.
Measuring in inches: divide by 1,728, or let the unit selector work
Tape measures read in inches, so this is the most common cubic footage job of all. Multiply the three sides in inches to get cubic inches, then divide by 1,728, because 12 x 12 x 12 = 1,728 cubic inches fill one cubic foot. A box of 36 x 24 x 12 inches holds 10,368 cubic inches, and 10,368 / 1,728 = 6.00 cubic feet. Set the box mode to inches and enter the same three numbers and you get the identical 6.00 ft³, plus a surface area of 22.00 ft², with each side shown converted to feet (3, 2, and 1 ft) in the steps.
One warning from carrier practice: for shipping, measure the outside of the sealed package at its longest points. Carriers price the space the package occupies, and dimensional weight calculations start from those outer cubic inches, not from the product inside. If you need the area of the space itself rather than its volume, for example the floor a unit covers, the coverage area calculator works in square units.
From cubic feet to a bulk order: coverage by depth
Landscaping material is sold by the cubic yard, and one cubic yard is 27 cubic feet spread over an area at a chosen depth. The floor area mode plus this coverage table covers most mulch, soil, and gravel estimates: work out your volume, then read the cubic yards line, which this calculator shows to three decimals precisely because small beds produce fractions like 0.926 yd³ that vanish at one decimal.
So the worked mulch example, 50 square feet at 6 inches (0.5 ft), needs 25.00 ft³, which is 0.926 yd³: order one yard and you will have a small surplus for settling, which is the right side to err on with organic material. When the volume becomes a pour rather than a spread, the concrete volume calculator continues from cubic yards into slab and footing quantities.
What most cubic footage calculators miss
The top-ranking tools reviewed for this page handle a plain box competently, and then stop. The gaps below are the reasons this page keeps its three modes.
Miss 1: no floor area mode. Rooms, storage units, and garden beds are usually known by their square footage first. Forcing that through a box form means inventing a length and width that multiply to the same area, which is pointless arithmetic with two new chances to slip. Area times height is one multiplication, and it is a tab here.
Miss 2: cylinder by radius. As covered above, diameter is what gets measured. Tools that demand a radius produce fourfold errors from honest measurements, and the error survives because the answer still looks plausible.
Miss 3: two or three outputs. A volume that will be ordered in yards, dosed in liters, and rated in gallons needs all of its forms at once. Seven outputs per calculation, including surface area, means no second tool and no hand conversion between them.
Miss 4: hidden working. A bare number cannot be checked. Every result here lists the unit conversion and the multiplication in order, so a supplier, a teacher, or your own later self can audit the figure line by line.
One honest limit in the other direction: there is no sphere mode and no per-side unit mixing. A sphere measured in feet belongs on the cu feet calculator linked above, and mixed units, say a length in feet with a width in inches, must be converted to one unit before entering.
Frequently Asked Questions
For a rectangular space: cubic feet = length x width x height, with all three measurements in feet. For a cylinder: volume = pi x radius squared x height. If you know the floor area in square feet, multiply it by the height in feet.
Multiply length x width x height in inches to get cubic inches, then divide by 1,728 (because 12 x 12 x 12 = 1,728 cubic inches per cubic foot). The calculator does this automatically when you select inches as the unit.
27. A cubic yard is 3 ft x 3 ft x 3 ft = 27 cubic feet. To convert cubic feet to cubic yards, divide by 27. Landscaping materials like mulch and topsoil are usually sold by the cubic yard.
Square feet measure area (two dimensions: length x width), while cubic feet measure volume (three dimensions: length x width x height). You cannot convert one to the other without knowing the third dimension, which is why the floor-area tab asks for height.
Measure the diameter and the height, halve the diameter to get the radius, then compute pi x radius squared x height. The cylinder tab does this for you: a 4 ft diameter, 10 ft tall tank holds 125.66 cubic feet.
The outside. Carriers charge for the space the package occupies, including the packaging itself, and dimensional-weight pricing is based on outer dimensions. Measure the longest points of the sealed box on all three sides.
Because a floor area on its own does not describe a closed shape. The same 50 square feet could be a 5 by 10 ft rectangle or an L-shaped room, and each has a different wall and edge area. The mode therefore reports volume and conversions only, and marks surface area as not applicable rather than inventing a shape.
Add This Calculator to Your Website
References
- National Institute of Standards and Technology, "Guide to the SI, Appendix B: Conversion Factors" - the source for the foot, yard, meter, and centimeter factors the calculator applies before multiplying. NIST: Guide to the SI, Appendix B. Accessed October 2026.
- National Institute of Standards and Technology, "SI Units: Length" - definitions of the length units behind the five input options. NIST: SI Units, Length. Accessed October 2026.
- National Institute of Standards and Technology, "Guide for the Use of the International System of Units (SI)" (Special Publication 811, full text) - conversion and rounding practice for the seven reported outputs. NIST: SP 811 full text (PDF). Accessed October 2026.
- Stewart, "Volume and Surface Area" lecture notes - derivations of the box and cylinder volume formulas and the cylinder surface area formula 2 pi r squared plus 2 pi r h. Stewart: Volume and Surface Area (PDF). Accessed October 2026.
- LibreTexts, "SI (Metric) Units" - an open textbook summary of how the cubic meter and the liter relate, for readers checking the metric outputs. LibreTexts: SI (Metric) Units. Accessed October 2026.