What Is a Foot?
A foot (symbol ft, sometimes written with a prime, 6′) is a unit of length in the imperial and US customary systems equal to exactly 0.3048 meters, or 12 inches. Three feet make a yard, and 5,280 feet make a mile. The value 0.3048 m is exact by definition: since the 1959 International Yard and Pound Agreement, the foot has been one-third of an international yard of 0.9144 m.
The unit is named after the human foot, and many ancient cultures had one. The Roman pes was about 29.6 cm, a little shorter than the modern foot. English feet varied from town to town until standard measures were set by statute, and even in the twentieth century the American and British feet differed by a few parts per million.
The United States kept a second foot for land surveying until recently. The US survey foot, 1200/3937 m, is about 0.3048006 m. The difference is only 2 parts per million, about 3.2 mm over a mile, but it caused real errors when survey coordinates were mixed. NIST retired the US survey foot at the end of 2022, so from January 1, 2023 the international foot is the single foot for all US uses.
Today the foot is still the everyday unit for a person’s height in the US and UK, for building and ceiling heights, for floor areas in square feet, and, almost worldwide, for aircraft altitude.
What Is a Mile?
A mile, in the sense used on roads and maps, is the international (statute) mile of exactly 5,280 feet. That number looks arbitrary, and it is a historical compromise. The Roman mile was mille passus, a thousand double paces of five Roman feet, or 5,000 feet. In England the furlong, the length of a plowed furrow, was already fixed at 660 feet, so a 1593 Act of Parliament under Elizabeth I set the mile at 8 furlongs. Eight times 660 is 5,280.
The 1959 agreement then tied that mile to the meter. With the foot at exactly 0.3048 m, the mile became exactly 1,609.344 m. The longer nautical mile used at sea is a separate unit of 1,852 m, or about 6,076 feet.
Altitudes and Heights in Miles
Heights of mountains, buildings and aircraft are usually given in feet, which makes them hard to picture as distances. Converting to miles helps: Everest is about as tall as a 5.5-mile walk is long. The values below are converted from published heights.
| Height or altitude | Feet (ft) | Miles (mi) |
|---|---|---|
| Statue of Liberty (ground to torch) | 305 | 0.0577652 |
| Empire State Building (to tip) | 1,454 | 0.275379 |
| Burj Khalifa | 2,717 | 0.514583 |
| Mount Whitney | 14,505 | 2.747159 |
| Denali | 20,310 | 3.846591 |
| Mount Everest | 29,032 | 5.498485 |
| Typical airliner cruising altitude | 35,000 | 6.628788 |
| Concorde cruising altitude | 60,000 | 11.36364 |
| Kármán line (edge of space, 100 km) | 328,084 | 62.13712 |
Burj Khalifa, the tallest building in the world at 828 m, reaches just over half a mile. Mount Everest’s summit at 8,848.86 m stands 5.5 miles above sea level, and the air there holds about a third of the oxygen found at the coast. Airliners cruise between roughly 31,000 and 42,000 feet, so passengers are typically 6 to 8 miles up.
Pilots work in feet nearly everywhere, even in metric countries, because air traffic control assigns altitudes in “flight levels” of hundreds of feet: flight level 350 means 35,000 feet, or 6.6 miles. The internationally recognized edge of space, the Kármán line at 100 km, is about 62 miles high.
How Many Feet in a Mile?
There are exactly 5,280 feet in one mile. A popular memory aid is “five tomatoes”, which sounds like “five-two-eight-oh”. Useful fractions follow from it: half a mile is 2,640 ft, a quarter mile is 1,320 ft, and a tenth of a mile is 528 ft.
To convert miles to feet, multiply by 5,280. A 5K race of 3.11 miles is 16,404 feet long, and a marathon covers about 138,435 feet.
City blocks make the number easier to picture. In Manhattan, the short blocks between numbered streets are about 264 feet, so 20 of them make a mile. On foot, an adult with a 2.5-foot stride takes 2,112 steps per mile, which is why a mile is often described as “about 2,000 steps”. The how many steps in a mile page shows how that changes with height.