Cubic Feet Volume Calculator

The cubic foot (ft³) is the workhorse volume unit of the imperial measurement system — the volume of a cube one foot long on every side. It shows up everywhere in construction, shipping, freight, landscaping, appliances, and storage. Concrete is ordered by the cubic yard (27 cu ft). Mulch is bagged by the cubic foot. Freight carriers price by cubic feet to recover trailer capacity. Refrigerators and freezers are sold by their interior cubic feet. Storage units are measured in cubic feet. Knowing how to calculate cubic feet for whatever shape you're working with — box, cylinder, sphere, cone, prism, or an irregular combination — is one of the most generally useful spatial skills you can have.

Real-world objects rarely fit a single neat primitive. A grain silo is a cylinder topped with a cone. A bay-window addition is a box plus a triangular prism. An L-shaped room is two rectangles added together. An above-ground pool is a cylinder. A spherical propane tank uses the sphere formula. A pickup-truck bed is a box with the wheel-wells cut out. This calculator handles every common shape with its own dedicated formula, lets you sum multiple shapes for irregular composites, and converts the result into the six most-used volume units the instant you press Calculate. The math is exact; the only thing you bring is the tape measure.

Beyond raw volume, this tool also estimates weight and cost. Enter a density in pounds per cubic foot (concrete is 150, water is 62.4, dry sand is 100, bagged mulch is 18–25) and you get the pound and kilogram weight of whatever you're calculating. Enter a price per cubic foot or per cubic yard and you get total project cost. This makes it a one-stop tool for both spatial planning and order quoting — whether you're sizing a concrete order, pricing topsoil for a bed, weighing a freight pallet, or figuring out how much water a tank holds.

The Formulas, Visualized

Volume Conversion Table

How to Use This Calculator

1. 1. Pick a Preset or Choose a Shape: Tap a quick preset like the 18×18×24 shipping box, 12" Sonotube, 4-foot spherical tank, or 10×12×8 room to auto-fill dimensions. Otherwise pick from Box, Cylinder, Sphere, Hemisphere, Cone, Triangular Prism, or Trapezoidal Prism.
2. 2. Set the Unit: Each shape has its own unit selector — inches, feet, yards, centimeters, or meters. Use the most natural unit for what you're measuring; the calculator handles the conversion to cubic feet automatically.
3. 3. Enter Dimensions: Fill in the fields for your shape (length, width, height for a box; diameter and height for a cylinder; etc.). For circular shapes always enter diameter — the calculator computes radius internally to keep things foolproof.
4. 4. Add More Shapes for Irregular Volumes: Switch to Multiple Shapes mode and tap "Add Another Shape" to add a box for the main body, a cone for a roof, a cylinder for a column, and so on. Each shape can have its own unit and quantity. The total is the sum of every shape.
5. 5. Optional: Weight & Cost: Enter a density in lbs per cubic foot (e.g. 150 for concrete, 100 for dry sand, 25 for bagged mulch) to get total weight in pounds and kilograms. Enter a price per cubic foot or per cubic yard to get a project cost estimate.

Common Use Cases

Pro Tips for Accurate Volumes

• • Convert units before you multiply — or let the tool do it. The single most common cubic-feet mistake is mixing inches and feet inside the same multiplication. A 2 ft × 3 ft × 6 in box is not 36 cu ft — it's 3 cu ft once you convert 6 in to 0.5 ft. This calculator has a unit dropdown on every shape so you never have to remember.
• • Irregular = sum of simple shapes. Don't try to fit a single formula to a weird object. Break it into a box plus a cylinder, or two boxes plus a triangular prism, and add. Switch to Multiple Shapes mode and add an entry per piece.
• • Account for waste, compaction, and over-excavation. For concrete pours add 5–10%. For bulk gravel allow for compaction (a 20% safety factor is common). For loose-fill mulch and topsoil add 5% for settling.
• • Diameter, not radius, for circular shapes. Measuring radius requires you to find the exact center of a circle, which is hard with a tape measure. Diameter is easy — just span the widest point. This calculator asks for diameter and squares the half internally.
• • For tanks and pools, measure interior dimensions. Outside dimensions include wall thickness, which inflates your volume. Always measure inside-to-inside for fluid-holding volumes.
• • For shipping, use the longest dimension. Freight carriers bill the bounding-box volume of irregular cargo, not the actual shape. A 10 ft long pipe that's only 2 inches diameter still occupies a 10 ft × 1 ft × 1 ft volume slot on the truck.

Worked Examples

Whether you're estimating a concrete order, packing a moving truck, pricing topsoil, sizing an HVAC system, calculating tank capacity, or just figuring out how many cubic feet that weird-shaped freezer holds, this calculator gets you a defensible number in seconds. Bookmark it, share it, and use it the next time someone asks "how much does that hold?"