Cubic Feet Calculator

Important limitations

Cubic Feet Calculator is limited to the finite inputs, modes, and outputs stated for the Rectangular prism volume with independent units method. Check length, length unit, width, width unit, and height or depth, validation messages, the equation, and the stated display precision before relying on volume.

Review the stated scope, calculation method, assumptions, supported inputs, and effective dates, and obtain qualified advice before using a high-stakes result.

This formula passed its registered engineering tests and is published under an explicit site-owner policy authorization. No independent expert, QA, editorial, legal, or third-party review is claimed. Verify consequential results with a qualified professional.

Cubic-foot and cubic-yard planning toolkit

Calculate cubic feet and keep cubic yards visible

Choose a solid, mix length units freely, and see cubic-foot and cubic-yard equivalents together without turning geometric volume into a material quote.

12 methods8 input units11 volume units

1

Choose a methodAll twelve calculators stay open below.

2

Mix units freelyEach length has its own unit.

3

Choose an outputUse cubic units, liters, or US gallons.

Reproducible examples

Try a hand-check, a real use case, or mixed units

Three-foot cube

A simple hand-check for a box-shaped space.

3 × 3 × 3 = 27 ft³, exactly 1 yd³.

Microwave cavity

Interior measurements are 19 in by 14 in by 10 in.

2,660 in³ ÷ 1,728 = 1.539352 ft³.

Mixed-unit storage bay

A bay measures 4 ft by 30 in by 0.8 m.

Normalize each edge first; the volume is 8.39895 ft³.

Shallow landscape bed

A 20 ft by 8 ft bed receives 3 in of material.

40 ft³ ÷ 27 = 1.481481 yd³ before any ordering allowance.

One-yard coverage

A known 108 ft² area receives a uniform 3 in depth.

108 ft² × 3 in = 27 ft³ = exactly 1 yd³.

Cubic-yard reference

One cubic yard across a uniform depth

1 yd³ = 27 ft³

Coverage in square feet equals 324 divided by depth in inches. At 3 in, one full cubic yard covers exactly 108 ft²; a 10 ft × 10 ft shortcut is approximate rather than a full yard.

Exact area covered by one cubic yard
Depth	Coverage
1 in	324 ft²
2 in	162 ft²
3 in	108 ft²
4 in	81 ft²
5 in	64.8 ft²
6 in	54 ft²
12 in	27 ft²

01 · Box-shaped solid

Rectangular Prism

V = l × w × h

Multiply three mutually perpendicular dimensions.

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Each dimension may use a different unit.

02 · Base area already measured

Known Area + Height

V = A × h

Use a measured base area and its perpendicular height or depth.

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Each dimension may use a different unit.

03 · Perfectly round solid

Sphere

V = ⁴⁄₃πr³

Radius runs from the center to any point on the surface.

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Each dimension may use a different unit.

04 · Circular base · one apex

Cone

V = ⅓πr²h

Height is perpendicular from the circular base to the apex.

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Each dimension may use a different unit.

05 · Six equal square faces

Cube

V = s³

One edge length determines the complete cube.

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Each dimension may use a different unit.

06 · Two circular bases

Cylinder

V = πr²h

Use the perpendicular distance between the circular bases.

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Each dimension may use a different unit.

07 · Cylinder with hemispherical ends

Capsule

V = πr²h + ⁴⁄₃πr³

Height h is only the straight cylindrical section, excluding both caps.

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Each dimension may use a different unit.

08 · Slice of a sphere

Spherical Cap

V = πh²(3R − h) ÷ 3

Cap height h may not exceed the full sphere diameter 2R.

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Each dimension may use a different unit.

09 · Cone with its tip removed

Conical Frustum

V = ⅓πh(R² + Rr + r²)

Enter both parallel circular radii and their perpendicular separation.

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Each dimension may use a different unit.

10 · Three semi-axes

Ellipsoid

V = ⁴⁄₃πabc

Use the three center-to-surface semi-axes, not full diameters.

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Each dimension may use a different unit.

11 · Square base · one apex

Square Pyramid

V = ⅓s²h

Height is perpendicular from the base center to the apex.

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Each dimension may use a different unit.

12 · Hollow circular cylinder

Tube

V = ¼π(D² − d²)L

Material volume uses outer and inner diameters; inner must stay smaller.

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Each dimension may use a different unit.

Interior capacity and site volume

Calculate cubic feet and convert measured volume to cubic yards

Cubic feet describe occupied three-dimensional space. Measure a box, room, storage cavity, or uniform-depth project once, then keep the exact cubic-yard equivalent visible when a downstream supplier uses yd³.

Step-by-step guide · Interior capacity and site volume

Normalize mixed tape readings before multiplying

Prism rule: V = L × W × H
Cube identity: 12 in × 12 in × 12 in = 1 ft³
Scale: 27 ft³ = 1 yd³

Attach a unit to each edge
Record 4 ft, 30 in, and 0.8 m as three labelled values. Never multiply bare numbers and decide the cubic unit afterward.
Convert into one length system
Change inches to feet or all dimensions to metres, retaining enough digits for the final multiplication. Unit conversion happens before the geometry.
Cube the unit through the product
Feet times feet times feet produces cubic feet. A square-foot label at this stage signals that height was omitted.
Round at the reporting stage
Carry the unrounded volume into a later cost or capacity comparison, then report digits consistent with the least precise field measurement.

Calculate cubic feet and convert measured volume to cubic yards: Cubic feet describe occupied three-dimensional space. Measure a box, room, storage cavity, or uniform-depth project once, then keep the exact cubic-yard equivalent visible when a downstream supplier uses yd³.

Measure the usable cavity rather than its packaging

For storage or appliance capacity, the relevant dimensions are usually inside clear dimensions. Exterior trim, wall thickness, shelving, a compressor hump, or an open door can make the gross bounding box larger than the usable cavity. State which boundary you measured. For a room-air calculation, finished interior faces may be appropriate; for shipping, the carton exterior may be the carrier-facing dimension.

The rectangular-prism equation multiplies three perpendicular dimensions. It does not describe a sloped attic, cylinder, hopper, or object with rounded corners unless those irregular portions are separately modeled. A 10 ft by 6 ft by 3 ft rectangular space contains 180 ft³ because all three measures describe the same orthogonal volume.

Normalize mixed tape readings before multiplying

Attach a unit to each edge
Record 4 ft, 30 in, and 0.8 m as three labelled values. Never multiply bare numbers and decide the cubic unit afterward.
Convert into one length system
Change inches to feet or all dimensions to metres, retaining enough digits for the final multiplication. Unit conversion happens before the geometry.
Cube the unit through the product
Feet times feet times feet produces cubic feet. A square-foot label at this stage signals that height was omitted.
Round at the reporting stage
Carry the unrounded volume into a later cost or capacity comparison, then report digits consistent with the least precise field measurement.

Separate geometric volume from what the space can hold

Gross room volume

Length times width times height describes the room shell, not the volume displaced by furniture, ductwork, insulation, or stored goods.

Packed shipment capacity

Objects rarely pack without gaps. A packing factor is a scenario input derived from the product and arrangement, never a universal deduction from cubic feet.

Loose material demand

Aggregate settling, moisture, and compaction change purchasing mass and delivered volume. Use a material-specific tool rather than treating a geometric box as a supplier quote.

Convert yardage without inventing an order quantity

Exact one-yard coverage check

One cubic yard is exactly 27 ft³. At a uniform 3 in depth, divide 27 ft³ by 0.25 ft to get 108 ft² of coverage. A 10 ft by 10 ft bed at that depth uses 25 ft³, or about 0.925926 yd³, so the familiar 10-by-10 shortcut is approximate rather than one full cubic yard.

Bank, loose, and compacted conditions

Measured excavation dimensions describe an in-place geometric volume. Loose delivery and compacted placement can differ because gradation, moisture, handling, lift thickness, and project requirements vary. No universal swell or compaction factor is inferred from the cubic-foot or cubic-yard result.

Commercial basis and named adjustments

Confirm whether a quote is per cubic yard, ton, truck, or bag and whether delivery minimums apply. Keep spillage, grade tolerance, compaction, and minimum-order rounding as separate, named entries supported by the supplier or project documents; geometry alone cannot supply material weight or price.

Continue only when the downstream quantity is known

A landscape bed that needs stone should continue in the gravel quantity and cost calculator because material density and price must remain declared. A slab or footing belongs in the concrete project calculator, which distinguishes geometry from bag yield. For a water enclosure with changing depth, use the pool volume calculator instead of forcing an average-height box without documenting the depth profile.

If the sole task is purchasing bulk material sold by the cubic yard, preserve this calculated volume and convert units with the exact relationship. Do not add an unnamed percentage during conversion; settlement, spillage, and over-excavation must be visible project decisions.