Calculate cubic feet for boxes, cylinders, cones, and spheres. Add multiple rooms or areas and convert to cubic yards, meters, and more.
Cubic Feet
960.00
ft³
The cubic foot is one of the most versatile and frequently used volume measurements in American daily life, bridging the gap between the small-scale cubic inch (used for engine displacement and small containers) and the large-scale cubic yard (used for bulk landscape materials and concrete). It is the volume measurement most Americans instinctively reach for when sizing appliances, storage spaces, moving trucks, and home improvement materials — making a reliable cubic feet calculator an indispensable tool for homeowners, contractors, and logistics professionals alike.
A cubic foot is a unit of volume equal to the space occupied by a cube with sides measuring exactly one foot (12 inches) in every direction. It contains 1,728 cubic inches, equals approximately 0.028317 cubic meters, and is exactly 1/27th of a cubic yard. The cubic foot is the dominant volume unit in US construction, real estate, HVAC engineering, appliance ratings, and bulk materials purchasing.
Volume measurement in cubic feet appears across a remarkable range of everyday contexts. Appliance manufacturers rate refrigerators, freezers, dishwashers, and washing machines in cubic feet of usable interior space. Moving companies size their trucks in cubic feet. HVAC engineers calculate heating and cooling loads based on the cubic footage of conditioned space. Bulk materials — topsoil, gravel, mulch, concrete — are estimated in cubic feet and ordered in cubic yards (27 cubic feet each). Freight carriers convert package dimensions to cubic feet when applying dimensional weight pricing.
The four fundamental shapes each have their own cubic feet formula. Rectangular boxes (including rooms, tanks, raised beds, and storage units) use length × width × height. Cylinders (tanks, columns, pipes, tree trunks) use π × radius² × height. Cones (stockpile mounds, hoppers, conical roofs) use (1/3) × π × radius² × height. Spheres (tanks, balls, domes) use (4/3) × π × radius³. In every case, all dimensions must be in feet before multiplying, or converted after using the appropriate conversion factor.
Understanding the difference between cubic feet and square feet prevents a fundamental measurement error. Square footage is a 2-dimensional area measurement — the footprint of a floor or surface. Cubic footage is 3-dimensional volume — how much three-dimensional space something contains. A 200 square foot room with 10-foot ceilings contains 2,000 cubic feet of air and volume. Adding the ceiling height transforms the flat area into a volumetric measurement useful for heating, cooling, and ventilation calculations.
The US relationship between cubic feet and other volume units creates useful benchmarks. One cubic foot holds 7.48 US gallons of water and weighs 62.4 pounds when full. A cubic foot of concrete weighs about 150 pounds. A cubic foot of dry sand weighs 95–125 pounds depending on moisture content and packing density. A cubic foot of dry gravel weighs about 100 pounds. These weight-per-cubic-foot figures — called bulk density or unit weight — are essential for structural calculations whenever large volumes of material must be supported.
The calculator handles unit conversion automatically. Enter your measurements in any unit — inches, feet, yards, centimeters, or meters — and the calculator converts them to feet before applying the volume formula. This eliminates the most common calculation error: mixing units within a single formula. Select the shape (box, cylinder, cone, or sphere) and enter the appropriate dimensions for that shape. The result displays in cubic feet plus four other common units: cubic yards, cubic meters, cubic inches, and US gallons.
The multi-area feature lets you add multiple spaces or objects and calculate their combined total. For a home project spanning multiple rooms, add each room as a separate entry and the totals section shows the cumulative volume. This is particularly useful when ordering bulk fill material for multiple garden beds, calculating total storage across different storage units, or sizing an HVAC system for an entire floor plan with variable ceiling heights.
For material ordering purposes, the calculated cubic footage is your baseline — but always order more than the bare calculation suggests. Bulk materials settle after delivery, compressed soil expands when moved, and irregular spaces always have voids that increase real-world consumption. A 10% buffer covers most residential projects; experienced contractors use 15% for irregular shapes and landscaping applications where precise coverage matters less than having enough on-site to complete the job without a second delivery.
For complex shapes that combine multiple geometric forms — a room with a vaulted ceiling section, a pool with a shallow ledge and deep end, or a cylindrical tank with a conical bottom — calculate each geometric component separately and sum the volumes. The multi-area calculator is designed exactly for this: add each distinct shape as a separate entry, label it clearly, and the sum gives your total volume with all components included.
The calculator also outputs cubic yards and cubic meters alongside cubic feet, letting you cross-check material quantities against supplier invoices that may use different units. This is especially useful when comparing quotes from suppliers who work in different unit systems — a mulch supplier quoting by the cubic yard and a bagged product from a home center priced by the cubic foot. Having all unit equivalents on screen at once eliminates the mental math that leads to ordering errors.
Length × Width × Height (Box)
The three dimensions of a rectangular prism in feet. All three must be in the same unit before multiplication. This formula applies to rooms, tanks, storage spaces, raised beds, and any box-shaped container.
Radius vs. Diameter
Cylinder and sphere formulas require the radius — half the diameter. Measure across the widest point to get the diameter, then divide by 2. Using diameter instead of radius inflates volume by a factor of 4.
Height (Depth) for Fill Calculations
When calculating fill material for a flat area, 'height' is the desired fill depth. Convert from inches to feet by dividing by 12. A 3-inch fill depth = 0.25 feet. A 6-inch depth = 0.5 feet.
Waste and Settling Factor
The multiplier applied to raw calculated volume when ordering materials. Use 1.10 (10% extra) for most projects. Use 1.15 for landscaping. Use 1.05 for precision concrete work where excess is costly.
Unit Weight (Bulk Density)
The weight of one cubic foot of a material. Water: 62.4 lb/ft³. Concrete: 145–150 lb/ft³. Gravel: 100–110 lb/ft³. Topsoil: 75–100 lb/ft³. Mulch: 10–30 lb/ft³. Multiply volume in cubic feet by unit weight to get total project weight for structural and transport planning.
Compaction and Swell Factors
Excavated soil swells 10–30% in volume when loosened (swell factor). Compacted fill settles 10–20% from loose state. When importing fill, order 15–20% more than the compacted volume you need. When disposing of excavated material, the truck needs 15–25% more volume than the in-place measurement.
Concrete Footing for a Deck Post
Inputs: Cylindrical tube form: 12" diameter × 48" deep
Result: 3.14 cubic feet (0.12 cubic yards)
Convert 12" diameter to 0.5 ft radius and 48" depth to 4 ft. Apply π × 0.25 × 4 = 3.14 cu ft. For 6 footings, order 0.75 cubic yards of concrete or approximately 34 bags of 80 lb ready-mix (each yields ~0.60 cu ft).
Fill Volume for a Raised Garden Bed
Inputs: Rectangular bed: 4 ft × 8 ft × 12 inches deep
Result: 32 cubic feet (1.19 cubic yards)
Convert 12 inches to 1 foot. Apply 4 × 8 × 1 = 32 cubic feet. Divide by 27 for cubic yards: 32 ÷ 27 = 1.19 yards. Order 1.25–1.3 yards to account for settling and minor spillage. At 2 cu ft bags, you would need 16 bags of soil mix.
Cylindrical Water Storage Tank
Inputs: Cylinder: 6 ft diameter × 8 ft tall
Result: 226.2 cubic feet (1,691 gallons)
Radius = 3 ft. Volume = π × 9 × 8 = 226.2 cubic feet. Multiply by 7.4805 to get gallons: 226.2 × 7.4805 = 1,691 gallons. At 62.4 lb per cubic foot, a full tank weighs 14,115 pounds — about 7 tons — requiring a reinforced concrete pad foundation.
Accurate cubic footage calculations directly determine project costs and outcomes. Under-ordering bulk materials means a second delivery charge that often costs as much as the additional material. Over-ordering means paying for material you cannot use and disposing of the excess — a cost in both money and labor. For concrete in particular, where a pour must be completed before the batch sets, running short mid-pour creates a structural problem that requires saw-cutting and starting over.
HVAC system sizing depends critically on the cubic footage of conditioned space. An undersized system runs constantly, wears out prematurely, and never fully heats or cools the space. An oversized system short-cycles — heating or cooling the space so quickly that it shuts off before removing enough humidity, leaving the space feeling clammy even when the temperature is correct. Manual J load calculations, the industry-standard HVAC sizing method, use room-by-room cubic footage along with insulation values, window area, climate data, and occupancy loads.
For shipping and freight, volumetric accuracy determines whether you pay actual weight or dimensional weight billing. Carriers calculate a "DIM weight" by dividing the package's cubic inches by a divisor (typically 139 for domestic US carriers). If this DIM weight exceeds the package's actual scale weight, you pay on the DIM weight. A large, light package in an oversized box can cost 3–4× more to ship than the same product in a right-sized box. Calculating the minimum cubic footage that contains your product enables intelligent packaging decisions.
In real estate and construction, cubic footage affects structural engineering, fire code compliance, ventilation requirements, and energy code compliance. Residential building codes specify minimum ceiling heights and room volumes for habitable spaces. Fire suppression systems are sized to deliver agent at a concentration based on room cubic footage within a specified time. Energy codes calculate allowable heating and cooling loads based on building volume and envelope area. Getting these numbers right matters from permit application through final inspection.
Pool and spa contractors use cubic footage extensively to size filtration systems, chemical dosing, and heating equipment. A pool's water volume in gallons determines chlorine dosing rates, turnover time (hours required to filter the entire volume once), and heater BTU requirements. A pool that measures 20 ft × 40 ft with an average depth of 5 feet contains 4,000 cubic feet × 7.48 = 29,920 gallons. At a recommended turnover of 8 hours, the required pump flow rate is 29,920 ÷ 8 ÷ 60 = 62.3 gallons per minute — directly sized from the calculated cubic footage.
Agricultural and landscaping applications also depend heavily on cubic footage. Soil amendment applications are prescribed in cubic feet per 100 square feet of bed area. Compost tea brewers are sized by the gallon, which converts directly to cubic feet. Silo and grain bin capacities are rated in bushels — one bushel of grain equals approximately 1.244 cubic feet — and total capacity planning requires understanding the cubic footage of cylindrical or hopper-bottom bins. Precision agriculture increasingly uses volumetric measurements for variable-rate application of fertilizers, lime, and organic amendments calibrated to soil test results on a field-by-field basis.
Mixing Units Within a Calculation
Multiplying 36 inches × 2 feet × 0.5 yards produces a meaningless number. Convert all measurements to the same unit — feet — before applying any volume formula. This is the single most common error in volume calculations.
Confusing Diameter and Radius
The cylinder and sphere formulas use radius (half the diameter), not diameter. If you measure a 4-foot wide tank and plug 4 into the radius field, you calculate a volume 4 times too large. Always divide diameter by 2 to get radius before applying the formula.
Forgetting the One-Third Factor for Cones and Pyramids
A cone has exactly one-third the volume of a cylinder with the same base and height. Omitting the (1/3) multiplier overestimates volume by 3×. The same applies to pyramidal shapes relative to a rectangular prism of equal base and height.
Not Adding a Waste and Settling Factor
Ordering exactly the calculated volume almost always results in a shortage. Bulk materials settle 5–15% after delivery. Irregular shapes leave gaps. Spills occur during placement. Add at least 10% to material orders, and 15% for landscaping applications.
Using Exterior Dimensions for Interior Volume
Appliance listings (refrigerators, freezers, microwaves) give interior usable volume. If you measure a refrigerator's exterior and calculate volume, you get a number 20–40% larger than the actual storage capacity. Always use interior measurements for storage calculations.
Ignoring Irregular Shape Components
A room with a closet alcove, bay window bump-out, or staircase intrusion is not a simple rectangle. Break complex spaces into component rectangles, calculate each volume separately, then add (or subtract for intrusions) to get the true total cubic footage.
Forgetting to Convert Cubic Feet to Cubic Yards for Bulk Orders
Landscaping suppliers sell material by the cubic yard, not cubic foot. Ordering '32 cubic feet' when you need '32 cubic feet' but the supplier hears '32 cubic yards' results in a massive overage. Always divide your cubic feet total by 27 and explicitly state 'cubic yards' when placing bulk material orders.
Once you know volume in cubic feet, multiply by a material's bulk density (weight per cubic foot) to get total weight. This is essential for structural loading calculations, truck weight limits, and soil compaction analysis. Water runs 62.4 lb/ft³; concrete is 145–150 lb/ft³; dry topsoil averages 75–100 lb/ft³; gravel runs 100–110 lb/ft³; dry sand is 90–110 lb/ft³. Moisture content can increase soil density by 20–30%, which matters for load calculations on soft subgrades.
For truck delivery of bulk materials, volume in cubic yards and weight in tons both constrain what a truck can carry. A standard tandem-axle dump truck carries 10–14 cubic yards of loose material, but may be legally limited to 14 tons on public roads. Dense materials like gravel (about 1.35 tons per cubic yard) hit the weight limit before the volume limit; light materials like bark mulch (about 0.2 tons per cubic yard) hit the volume limit first.
Many real-world volume problems involve shapes within shapes. A hollow cylindrical pipe: outer cylinder minus inner cylinder. A rectangular room with a circular column: room volume minus column volume. A pool with a shallow ledge: total rectangular volume minus the volume above the ledge depth in the deep end. These composite calculations always follow the same logic — compute the enclosing simple shape, then subtract the volumes of empty or excluded regions. This subtraction method works for any combination of the four basic shapes.
For construction estimating, the same additive and subtractive logic extends to earthwork. A foundation excavation that has a central deeper sump pit requires the main rectangular volume plus the additional sump pit volume. Grading cuts and fills across uneven terrain are divided into triangular prism sections (the average-end-area method used in civil engineering) and summed. Retaining wall backfill volumes subtract the volume of the wall footing from the total trapezoidal fill area. Getting these decompositions right prevents expensive under-bids and change orders.
Different industries use different volume reference units, and knowing how to translate between them saves time and prevents ordering errors. Concrete is ordered in cubic yards and each 80 lb bag yields 0.60 cubic feet — so 45 bags make one cubic yard. Mulch sold in 2 cubic foot bags requires 13.5 bags per cubic yard. Bagged topsoil (often sold in 40 lb or 1 cubic foot bags) needs 27 bags per cubic yard. Gravel sold in 50 lb bags at about 0.5 cubic feet per bag needs 54 bags per cubic yard — at which point bulk delivery is clearly more economical.
For liquid volumes in tanks and vessels, engineers often use gallons as the working unit because capacity labels (water heaters, pressure tanks, holding tanks) are in gallons. One US gallon = 0.1337 cubic feet = 231 cubic inches. A 40-gallon water heater contains 40 × 0.1337 = 5.35 cubic feet of water at full capacity, weighing 40 × 8.34 = 333 pounds. Understanding that a gallon weighs 8.34 pounds and occupies 0.1337 cubic feet gives you a mental shortcut for weight-from-volume estimation of any water-filled vessel.
| Cubic Feet | Cubic Yards | Cubic Meters | US Gallons | Liters |
|---|---|---|---|---|
| 1 | 0.037 | 0.028 | 7.48 | 28.3 |
| 5 | 0.185 | 0.142 | 37.4 | 141.6 |
| 10 | 0.370 | 0.283 | 74.8 | 283.2 |
| 27 | 1.000 | 0.765 | 201.9 | 764.6 |
| 50 | 1.852 | 1.416 | 374.0 | 1,415.8 |
| 100 | 3.704 | 2.832 | 748.1 | 2,831.7 |
| 270 | 10.000 | 7.646 | 2,019 | 7,645.5 |
| 500 | 18.519 | 14.158 | 3,740 | 14,158.4 |
| 1,000 | 37.037 | 28.317 | 7,481 | 28,316.8 |
How do I calculate cubic feet?
For a rectangular box, multiply length × width × height in feet. For a cylinder, use π × radius² × height. For a cone, use (1/3) × π × radius² × height. For a sphere, use (4/3) × π × radius³. Make sure all measurements are in feet before calculating.
How many cubic feet are in a cubic yard?
There are exactly 27 cubic feet in one cubic yard. Because one yard equals 3 feet, and volume is three-dimensional, you cube the conversion: 3 × 3 × 3 = 27. Landscaping materials like mulch and gravel are commonly sold by the cubic yard in bulk.
How do I convert cubic feet to cubic meters?
Multiply cubic feet by 0.028317 to get cubic meters. Conversely, multiply cubic meters by 35.3147 to get cubic feet. One hundred cubic feet equals 2.83 cubic meters.
How many cubic feet are in a gallon?
One US gallon equals approximately 0.1337 cubic feet. To convert gallons to cubic feet, multiply by 0.1337. To go from cubic feet to gallons, multiply by 7.4805.
How do I calculate cubic feet from inches?
Divide each inch measurement by 12 to get feet, then multiply. Alternatively, multiply all three inch measurements and divide by 1,728. A box measuring 24" × 18" × 12" = 5,184 cubic inches ÷ 1,728 = 3 cubic feet.
How many cubic feet does a refrigerator have?
Most refrigerators range from 18 to 28 cubic feet. Compact mini-fridges run 1.7 to 4.5 cubic feet. Standard side-by-side models are 22–26 cubic feet. The listed capacity is usable interior volume, not exterior dimensions.
How do I calculate cubic feet for a moving truck?
Moving trucks list cargo volume in cubic feet. A 10-foot truck holds about 368 cubic feet, a 15-foot truck about 764 cubic feet, and a 20-foot truck about 1,015 cubic feet. A furnished 1-bedroom apartment typically fills a 10–15 foot truck.
How do I find the cubic feet of an irregularly shaped space?
Break the space into simpler shapes, calculate each volume separately, and add them together. Subtract any permanently installed fixtures that reduce usable space.
What is the cubic footage formula for HVAC?
Room volume (cubic feet) = length × width × ceiling height. Required CFM = (Room cubic feet × Air changes per hour) ÷ 60. Residential HVAC typically provides 6–8 air changes per hour.
How do I calculate cubic feet for a fish tank?
Aquarium volume (cubic feet) = length (ft) × width (ft) × height (ft). Multiply by 7.4805 to convert to US gallons. A standard 55-gallon aquarium measures 48" × 13" × 21", which is about 7.58 cubic feet.
How many cubic feet is a cord of wood?
A full cord is 128 cubic feet of stacked wood (4 ft × 4 ft × 8 ft). Actual solid wood content is about 80–90 cubic feet; the rest is air between logs. A face cord is typically about 42–43 cubic feet.
What is the difference between cubic feet and square feet?
Square feet measures area (2D: length × width) while cubic feet measures volume (3D: length × width × height). To convert from square feet to cubic feet, multiply by the height dimension. A 200 sq ft room with 9 ft ceilings = 1,800 cubic feet.
How do I calculate cubic feet of soil or gravel needed?
Area (sq ft) × depth (ft) = cubic feet needed. Convert depth from inches to feet (divide by 12). A 10 × 20 ft bed at 6-inch depth = 200 × 0.5 = 100 cubic feet = 3.7 cubic yards.
What is the cubic footage of a standard bathtub?
A standard 60" × 30" bathtub holds approximately 5 cubic feet of water filled to the overflow. That is about 37–42 gallons at 7.48 gallons per cubic foot. Larger soaking tubs can hold 80–100 gallons.
How do I convert cubic feet to liters?
Multiply cubic feet by 28.3168 to get liters. One cubic foot equals 28.317 liters. A 2 cubic foot mini-fridge holds about 56.6 liters.
How do I calculate the volume of a cylinder in cubic feet?
Volume = π × radius² × height, with measurements in feet. A cylindrical tank 4 feet in diameter and 6 feet tall: radius = 2 ft; Volume = 3.14159 × 4 × 6 = 75.4 cubic feet = 563.5 gallons.
How many 2 cubic foot bags of mulch make a cubic yard?
13.5 bags of 2-cubic-foot mulch equals one cubic yard (27 ÷ 2 = 13.5). For 3-cubic-foot bags, you need 9 bags per cubic yard. Buying in bags typically costs 20–40% more per cubic foot than bulk delivery.
What is cubic footage used for in shipping?
Freight carriers use dimensional weight (DIM weight) based on package volume. DIM weight = (L × W × H in inches) ÷ 139 for domestic UPS/FedEx. If DIM weight exceeds actual weight, you are billed on the DIM weight.
How do I calculate the volume of a cone in cubic feet?
Volume = (1/3) × π × radius² × height. For a cone pile with 6-foot radius and 4-foot height: Volume = 0.3333 × 3.14159 × 36 × 4 = 150.8 cubic feet = 5.58 cubic yards.
How does a cubic feet calculator help with storage unit selection?
A 10 × 10 ft unit with 8 ft ceilings provides 800 cubic feet. A queen mattress and box spring is about 50 cubic feet; a sofa about 40–60 cubic feet. Estimate your belongings' total volume and compare to available unit capacities.
What is the cubic footage of a typical bedroom?
A typical US bedroom is 10 × 12 feet with 8-foot ceilings = 960 cubic feet. Master bedrooms run 12 × 14 to 14 × 16 feet = 1,344 to 1,792 cubic feet. Residential code requires minimum 70 sq ft and 7-foot ceilings.
How do I calculate cubic feet for a concrete footing?
Volume = π × radius² × height for cylindrical forms. A 12-inch diameter, 4-foot sono-tube: radius = 0.5 ft; Volume = 3.14159 × 0.25 × 4 = 3.14 cubic feet = 0.116 cubic yards. One 80 lb bag of concrete yields about 0.60 cubic feet.
What is the volume of a sphere in cubic feet?
Volume = (4/3) × π × radius³. A sphere with a 3-foot radius: Volume = 4.189 × 27 = 113.1 cubic feet. Spherical calculations apply to propane tanks, water towers, and dome structures.
How many cubic feet of air does a room contain?
Room air volume = length × width × height. A 15 × 20 ft living room with 9 ft ceilings = 2,700 cubic feet of air. Air at sea level weighs about 0.075 lb per cubic foot at 70°F.
How do I calculate cubic feet for a raised garden bed?
Length × Width × Height (feet) = cubic feet of fill needed. A 4 × 8 ft bed at 12 inches deep needs 4 × 8 × 1 = 32 cubic feet = 1.19 cubic yards. Add 5% for settling.
What is the cubic footage of a standard shipping container?
A 20-foot ISO container provides approximately 1,172 cubic feet of internal volume. A 40-foot standard container has about 2,385 cubic feet. A 40-foot high-cube container provides approximately 2,694 cubic feet.
Why do landscaping materials use cubic yards instead of cubic feet?
Quantities needed for meaningful coverage typically amount to several cubic yards — working in cubic yards gives more manageable numbers. One cubic yard = 27 cubic feet covers 324 sq ft at 1-inch depth or 108 sq ft at 3 inches.
How do I calculate the cubic feet of a pyramid shape?
Volume = (1/3) × base area × height. A square pyramid with a 6 × 6 ft base and 4 ft height: Volume = (1/3) × 36 × 4 = 48 cubic feet. This is the same one-third factor used in the cone formula.
How accurate is a cubic feet calculator?
Calculators are mathematically exact given the inputs. The main error source is measurement accuracy. For material orders, always add a 5–10% buffer. Experienced landscapers add 15% for settling and uneven distribution.
What does one cubic foot of water weigh?
One cubic foot of water weighs approximately 62.4 pounds (28.3 kg) at room temperature. This is critical for structural engineering — a pool or tank must be supported for this weight. A 500 cubic foot pool contains 31,200 pounds of water alone.
Share your thoughts
Help us improve The Free Calculator Site