The cubic foot is a unit of volume in customary and imperial measurement systems. By definition, one cubic foot is the space contained by a cube that measures one foot in length, one foot in width, and one foot in height. It is commonly written as ft³ or sometimes cu ft. For a concise overview, see the definition and basic notes.

Definition and basic properties

Mathematically, 1 ft³ = (1 ft) × (1 ft) × (1 ft). Because there are 12 inches in a foot, a cubic foot also equals 12³ = 1,728 cubic inches. When working with metric units, a cubic foot corresponds to about 0.0283168 cubic meters (m³), or roughly 28.3168 liters. Useful online calculators and conversion tables can help when converting non-integer quantities: conversion resources.

Common conversions

  • 1 ft³ ≈ 28.3168 liters
  • 1 ft³ ≈ 0.0283168 m³
  • 1 ft³ = 1,728 in³
  • 1 ft³ ≈ 7.48052 US gallons (≈ 6.2288 Imperial gallons)
  • Weight of water: 1 ft³ of fresh water ≈ 62.4 pounds (≈ 28.3 kilograms) under typical conditions

Practical uses and examples

Cubic feet are used widely in everyday and industrial contexts. Appliances such as refrigerators and freezers advertise interior capacity in cubic feet. Storage and cargo volumes are often expressed in cubic feet for small shipments. In heating, ventilation and air conditioning (HVAC), airflow rates use related measures like cubic feet per minute (CFM). Concrete, soil and other bulk materials are more often measured by the cubic yard, but small volumes commonly use cubic feet. For examples and calculators, see practical examples.

It is helpful to distinguish the cubic foot from other volumetric units: the cubic yard (1 yd³ = 27 ft³) is used for larger construction volumes; the board foot measures lumber by thickness, width and length rather than a true cubic volume; and the cubic meter is the SI base unit for volume. When reporting volumes applied to gases or liquids, temperature and pressure can change the mass associated with a given cubic foot, so such context is important in scientific or engineering use.

Simple calculation example: a box 2 ft × 3 ft × 4 ft has a volume of 2×3×4 = 24 ft³, which equals about 679.6 liters. Understanding the cubic foot and its common conversions helps compare capacities across systems and plan storage, shipping, or equipment sizing appropriately.