The foot is a unit of length for measuring medium distances, used primarily in the United States. Its length equals 12 inches, 1/3 of yard and exactly 0.3048 meters.
Just like the inch, the foot was defined in relation to the human body, most likely the shoe length of an adult. Depending on the region, its historic length varied between 27.2cm and 35.8cm. Almost every country and even many cities within individual countries had their own standardized foot length.
It took until 1959 to agree on the International Foot with a worldwide standard length of 30.48cm. Today, the United States are the only country to use the foot as an official measurement unit. Inofficially, the foot is still popular in Great Britain, e.g. to denote body height. One of the few usage areas worldwide is the measurement of flight altitude in international aviation.
Wikipedia lists over 70 historical standard lengths for the foot, of which a stunning 21 were defined in Germany alone.
| Feet | |
|---|---|
| Marathon | 138,435.0 |
| Race track "Mille Miglia" | 5,279,855.6 |
| Earth radius | 20,925,738.2 |
| Earth circumference | 131,480,288.7 |
| Distance earth ↔ moon | 1,261,154,855.6 |
| Distance earth ↔ sun | 490,793,241,469.8 |