Free cubic feet calculator
Calculate the exact volume in cubic feet for boxes, cylinders, spheres, or cones — then convert instantly to cubic yards or cubic metres to match your supplier's units.
On this page10 sections
Results converted from input unit to ft³, yd³, and m³.
Results are estimates. Consult a professional.
How the cubic feet calculator works
Cubic feet measure the three-dimensional space inside any shape. The formula changes with the geometry — a box uses all three straight measurements, while a cylinder, sphere or cone uses π because of the curve. This calculator picks the right formula for your shape, runs the arithmetic, and converts the result into cubic yards or cubic metres so you can match supplier units without a separate conversion.
Worked examples for each shape
Jordan needs to fill a raised garden bed that measures 6 ft long × 4 ft wide × 3 ft deep. Using the box formula: 6 × 4 × 3 = 72 cubic feet. The supplier quotes soil in cubic yards, so Jordan divides: 72 ÷ 27 = 2.67 cubic yards.
Sam has a round concrete planter with an inner radius of 1.5 ft and a height of 2 ft. Volume = π × 1.5² × 2 = 3.14159 × 2.25 × 2 = 14.14 cubic feet.
Common cubic feet scenarios
Use this table for quick estimates before you measure precisely. All dimensions are in feet; volumes are rounded to two decimal places.
| Shape | Dimensions (ft) | Cubic feet | Cubic yards |
|---|---|---|---|
| Box | 4 × 2 × 1 | 8.00 | 0.30 |
| Box | 6 × 4 × 2 | 48.00 | 1.78 |
| Box | 8 × 4 × 3 | 96.00 | 3.56 |
| Cylinder | r = 1, h = 2 | 6.28 | 0.23 |
| Cylinder | r = 2, h = 3 | 37.70 | 1.40 |
| Sphere | r = 1 | 4.19 | 0.16 |
| Sphere | r = 2 | 33.51 | 1.24 |
| Cone | r = 2, h = 3 | 12.57 | 0.47 |
Box = L × W × H; Cylinder = π × r² × h; Sphere = 4/3 × π × r³; Cone = 1/3 × π × r² × h. Divide cubic feet by 27 for cubic yards; multiply by 0.028317 for cubic metres.
When to use a cubic feet calculation
Cubic feet calculations come up whenever you order or move a bulk material — mulch, soil, concrete, gravel, sand, insulation or water. Knowing the volume before you buy prevents both the wasted trip for a second load and the costly over-order you can't return.
- Garden beds and planters. Most bagged soil lists coverage in cubic feet; bulk suppliers quote in cubic yards. Calculate the box volume, then divide by 27 to match the yard price.
- Mulch and gravel. A standard depth of 3 inches is 0.25 ft. Multiply your area in square feet by 0.25 to get cubic feet, then divide by 27 for yards.
- Concrete pours. Box formula for slabs and footings; cylinder formula for round piers. Add 10% waste to every order.
- Shipping and storage. Freight carriers bill on dimensional weight (volume × density). Knowing the cubic footage lets you estimate freight costs before the pallet ships.
- Hot tubs and tanks. Cylinder formula for round vessels; multiply cubic feet by 7.48 for US gallons.
How accurate is this cubic feet calculator?
The arithmetic is exact — the calculator uses full-precision π and the exact NIST conversion factors. If you enter accurate measurements the result is the true geometric volume of that shape to many decimal places.
Real-world volumes are rarely as exact as the geometry suggests. A garden bed's walls lean slightly; a concrete cylinder is not a perfect circle; bulk materials compact or settle. For construction and landscaping, add a 10–15% overage to any material order to account for waste, uneven surfaces and compaction. For spheres and cones, the formula applies to the full solid shape — hollow objects need the volume of the shell calculated separately.
Cubic feet terms defined
About this cubic feet calculator
This calculator runs entirely in your browser. No measurements, dimensions or results are sent to any server, and no account is needed. The formulas use full-precision constants and match results you would get by hand with a scientific calculator.
Need another volume or area tool? Browse our home & garden calculators for mulch, concrete, pool volume and more, or explore the full library of free calculators.