Cubic Feet Calculator

Work out cubic feet from any units — inches, feet, cm, metres or yards — for a box or a cylinder, with cubic yards, cubic metres, litres and gallons alongside.

Cubic feet — ft³
Cubic inches — in³
Cubic yards — yd³
Cubic metres — m³
Litres — L
US gallons — gal

How to Calculate Cubic Feet

Three steps, any unit in, cubic feet out.

1

Pick a shape

Use Box for anything rectangular — a room, a crate, a fridge, a shipping carton. Use Cylinder for a tank, tube, barrel or pipe, where you enter a radius and a height instead.

2

Choose your unit and measure

Set the unit to whatever you measured in — inches, feet, centimetres, metres or yards — then type the dimensions. The calculator converts everything to feet before it multiplies, so you never have to do the conversion yourself.

3

Read the volume

Cubic feet is the headline number, with cubic inches, cubic yards, cubic metres, litres and gallons beside it. Need to trim the decimals to a tidy figure? The Rounding Calculator rounds to any place or significant figure.

Frequently Asked Questions

How do I calculate cubic feet from inches?
Multiply length by width by height in inches, then divide by 1,728, because there are 1,728 cubic inches in a cubic foot (12 × 12 × 12). For example, a box 24 × 24 × 24 inches is 13,824 cubic inches, which is 13,824 ÷ 1,728 = 8 cubic feet. This calculator does it for you: set the unit to inches, type the three dimensions, and it converts to feet before multiplying, so the answer comes out directly in cubic feet along with the other units.
What is the formula for cubic feet?
For a rectangular box the volume is length × width × height, with all three measured in feet. If your measurements are in another unit, convert each to feet first: divide inches by 12, multiply metres by 3.281, multiply yards by 3, or multiply centimetres by 0.03281. For a cylinder the formula is π × radius² × height. A tank 1 foot across (0.5 ft radius) and 2 feet tall holds π × 0.25 × 2 ≈ 1.571 cubic feet.
How many cubic feet are in a cubic yard?
There are 27 cubic feet in a cubic yard, because a yard is 3 feet and 3 × 3 × 3 = 27. So to convert cubic feet to cubic yards you divide by 27, and to go the other way you multiply by 27. This matters for ordering concrete, mulch, gravel or soil, which are usually sold by the cubic yard. The calculator shows cubic yards next to cubic feet automatically, so you can size an order without doing the division yourself.
How do I find the cubic feet of a cylinder or tank?
Switch to the Cylinder shape and enter the radius and the height. The radius is half the diameter, so if you measured across the top, halve that number first. The volume is π × radius² × height. For a barrel 2 feet across and 3 feet tall, the radius is 1 foot, so the volume is π × 1² × 3 ≈ 9.42 cubic feet, which is about 70.5 US gallons. The calculator converts your units to feet first, so you can measure in inches or centimetres and still read the answer in cubic feet.