Calculate volume in cubic feet from length, width, and height with instant unit conversions
Quick Examples — click to fill:
The volume of a rectangular prism equals the product of its three perpendicular dimensions. All labels update in real time as you type.
Where L, W, and H are all measured in feet. If your measurements are in inches, divide each by 12 before multiplying, or calculate cubic inches and divide by 1,728.
From inches:
A cubic foot (ft³) is a unit of volume defined as the space occupied by a cube whose sides are each exactly one foot long. Because volume is a three-dimensional measurement, a cubic foot represents 12 inches × 12 inches × 12 inches, which equals 1,728 cubic inches. This makes cubic feet one of the most commonly used volume units in the United States for everyday applications ranging from shipping boxes to HVAC duct sizing.
It is important to distinguish cubic feet from square feet. Square feet (ft²) measure area, a two-dimensional quantity such as the floor space of a room. Cubic feet measure volume, a three-dimensional quantity that accounts for depth or height. A room with 200 square feet of floor area and 9-foot ceilings contains 1,800 cubic feet of air volume — a critical number for heating and cooling engineers.
The volume of any rectangular prism (box) is derived from the fundamental geometric principle that volume equals the area of the base multiplied by the height:
All three dimensions must share the same unit before multiplying. If your measurements are in different units, convert them first:
Shipping & Freight
Carriers charge by dimensional weight calculated from cubic feet. Knowing your package's volume helps you select the right box size and avoid oversized fees.
Storage Units
Storage facilities are rated by cubic feet capacity. A 10×10×10 unit holds 1,000 ft³ — enough for a 2-bedroom apartment's contents.
HVAC & Ventilation
Engineers calculate cubic feet of room volume to size air handlers, furnaces, and ventilation systems, ensuring correct air changes per hour.
Concrete & Materials
Concrete is sold by the cubic yard (27 ft³). Calculate ft³ needed and divide by 27 to order the right number of yards for slabs or footings.
Landscaping
Mulch, topsoil, and gravel are sold by the cubic yard. Measure your garden bed in feet, calculate cubic feet, then convert to yards for ordering.
Aquariums & Tanks
Tank volume in cubic feet × 7.48 gives gallons, helping you match filtration capacity to actual water volume.
Every conversion factor has a precise mathematical origin:
Forgetting to convert units
Mixing feet and inches is the most common error. Always convert all three dimensions to the same unit before multiplying.
Confusing 2D with 3D
Square feet measure area (floor, wall, or ceiling surface). Cubic feet measure enclosed space. A 10×10 room has 100 sq ft of floor but 900 cubic feet of volume at 9-ft ceiling height.
Using interior vs. exterior dimensions
For containers, always measure the interior dimensions to get usable volume. Wall thickness can reduce actual capacity by 10–15%.
Rounding too early
Round only the final answer. Rounding intermediate dimensions introduces compounding errors, especially for large volumes.
Interactive volume lessons with visual examples and formulas for common shapes
Official unit conversion standards from the National Institute of Standards and Technology
Official US government definitions for construction measurements and volume calculations