The meter is the base SI unit of length. It was first defined in 1793 as one ten-millionth of the distance from the equator to the North Pole through Paris. Today it is defined as the distance light travels in vacuum in 1/299,792,458 of a second โ a definition tied directly to the universal speed of light. The meter is the foundation of the metric system used by 95% of the world.
Real-world: A standard door is about 2 metres tall. An Olympic swimming pool is exactly 50 metres long. The Eiffel Tower is 330 metres tall.
Read full meter reference โThe foot equals 30.48 centimeters exactly and is one of the oldest length units in human history. It is the international aviation standard for altitude โ commercial airliners cruise at 35,000 feet. In the US, building dimensions, human height and elevation are all expressed in feet. 1 foot = 12 inches.
Real-world: Airliners cruise at 35,000 ft (10.7 km). Mount Everest is 29,032 ft (8,849 m). A standard US ceiling is 8 ft (2.44 m).
Read full foot reference โ