Cubic Feet Calculator

Enter three dimensions, click Calculate. This cubic feet calculator gives the volume of any box-shaped space instantly, right on the page.

• Length (ft) — the longest horizontal side, such as 12 in the calculator's default
• Width (ft) — the other horizontal side, such as 3
• Height (ft) — the vertical side, such as 2

Measure all three sides in feet, fill the boxes, and the cubic feet calculator returns the same volume four ways: 72 cubic feet, 2.6667 cubic yards, 2.0388 cubic meters, and 2038.81 liters. Whichever unit your project quotes, the answer is already converted.

This page is more than a static cubic feet calculator — it is also an AI tutor you can ask questions:

• Ask in plain words. “My raised bed is 12 ft long, 3 ft wide, and 2 ft deep — how many cubic feet of soil do I need?” The AI reads it and solves it step by step.
• Take a photo of your homework. No typing: the AI reads the dimensions and shows every step.
• Ask about the ideas, not just the number. “Why does the unit have three factors of feet?” The AI explains — and you can check every number against the cubic feet calculator on this page, so nothing is guessed.
• Keep asking follow-ups. Inches, cylinders, L-shaped rooms — ask “how do I handle this?” as often as you need: the cubic feet calculator page keeps teaching.

A cubic foot is the space of a box one foot long, one foot wide, and one foot tall. Stack those small boxes inside any larger box and you have measured it in cubic feet — volume, the three-dimensional amount of room something takes.

For box-shaped spaces, one multiplication finds it:

$V = l \times w \times h$

The unit is the multiplication talking: $\text{ft} \times \text{ft} \times \text{ft} = \text{ft}^3$ — three factors of feet, hence cubic feet. That is also the whole trick of using a cubic feet calculator: all three sides must be in feet before you multiply. Mix units inside one product and the number that comes out means nothing.

Example — a garden bed. A raised bed measures 12 ft long, 3 ft wide, and 2 ft deep. How much soil does it hold?

1. Multiply length by width: $12 \times 3 = 36$.
2. Multiply by the height (depth): $36 \times 2 = 72$.
3. The bed holds 72 cubic feet of soil.

Those are the cubic feet calculator's default numbers — click Calculate above and 72 comes back in the first row, with the yard, meter, and liter conversions beside it.

Then one division turns volume into shopping units. Soil ships in 2-cubic-foot bags:

$72 \div 2 = 36 \text{ bags}$

That is the everyday rhythm of the cubic feet calculator: measure, multiply once, then convert the answer into whatever the store sells. And the order of the multiplication never matters — height first or length first, the same three factors give the same box.

Volume gets quoted in many units; the cubic feet calculator converts every answer for you. This is the table it uses:

Why 27? A cubic yard is a yard long in each direction, and $3 \times 3 \times 3 = 27$ cubic feet. Liters come from the metric side: at about 28.3168 liters per cubic foot, the default 72 cu ft reads $72 \times 28.3168 \approx 2038.81$ L — the same number the cubic feet calculator prints.

Inches first, feet second. Tape measures read inches, but the boxes want feet. Convert before multiplying: divide each measurement by 12. A box of 36 in × 24 in × 18 in is $3 \times 2 \times 1.5$ ft, so $V = 3 \times 2 \times 1.5 = 9$ cubic feet. Multiply the raw inches instead and you get 15552 cubic inches — a different unit that must be divided by $12^3 = 1728$ to land back at 9. Convert first, multiply once.

Not everything is a box. Two shapes cover most of the rest:

• Cylinders. Tanks, silos, round planters: $V = \pi r^2 h$, with $r$ the radius and $h$ the height — both in feet, so $V$ lands in cubic feet. If you measured the diameter, halve it before squaring: that slip multiplies the volume by 4. (The site's cylinder volume calculator works this case in full.)
• L-shapes. An L-shaped room or raised bed is two boxes. Split it at the notch, measure each rectangle, run the cubic feet calculator on each part, and add the two volumes.

The habit generalizes: chop the shape into pieces you can multiply — boxes and cylinders — compute each in feet, then combine. Leftover odd corners are small: estimate them as a shallow box rather than skipping them.

1. Stopping at square feet. Area carries two factors of feet (ft²); volume needs three (ft³). Square feet × height is a fine route to cubic feet — square feet alone is not a volume.
2. Feeding in inches. Inches × inches × inches gives cubic inches, 1728 times bigger. Convert every side to feet first (divide by 12), as the block above shows.
3. Diameter as radius. In $V = \pi r^2 h$, $r$ is the radius — half the diameter. Squaring the diameter quadruples the volume, and the tank overflows.

One habit prevents all three: write the unit next to every number as you work, and check that the units cancel to ft³ before trusting the cubic feet calculator's answer. When a result looks too big or too small, re-measure the shortest side first — that is the dimension most often typed wrong.