What is a Foot?

The foot equals exactly 0.3048 meters or 12 inches under the 1959 international agreement. The unit's name reflects its ancient origin as the length of an adult human foot, with measurements varying by region — from 250 mm to over 330 mm — until standardization. The foot is the dominant unit for human height in the United States and the United Kingdom (a person is described as '5 ft 10 in' rather than 178 cm), for building heights, and for aviation altitudes (worldwide aircraft fly at altitudes given in feet, even in metric countries). It remains the standard for residential floor counts, ceiling heights, and ladder ratings. The foot relates to the meter (1 ft ≈ 0.305 m), the yard (3 ft = 1 yd), and the mile (5,280 ft = 1 mi).

Visual reference for how the foot relates to other length units. Each row links to the full converter for that pair.

See all 15 length units in matrix view →

• Aircraft cruising altitude in international aviation
• US building heights, ceiling heights and room dimensions
• Mountain elevations on global maps (Everest = 29,032 ft)

• ✓1 foot = 12 inches = 30.48 cm exactly. Knowing feet gives you inches instantly.
• ✓For a quick metric estimate, multiply feet by 0.3 — 10 ft ≈ 3 m.
• ✓Pilots and air-traffic control use feet globally, even over metric countries.

• ✗Writing "6.2 ft" to mean "6 feet 2 inches" — the decimal form is 6.167 ft, not 6.2.
• ✗Confusing feet (length) with square feet (area) in US real-estate listings.
• ✗Using 0.3 instead of 0.3048 on structural drawings — errors accumulate on multi-storey buildings.