What is a Meter?

The meter is the base SI unit of length. Originally defined in 1793 as one ten-millionth of the distance from the equator to the North Pole through Paris, it has been redefined several times for greater precision. Since 1983, the meter has been defined by the speed of light: the distance light travels in vacuum during 1/299,792,458 of a second. This definition links the meter to a fundamental physical constant, making it reproducible anywhere in the universe. The meter is the parent unit for all metric lengths — kilometers, centimeters, millimeters — and is used globally in science, engineering, construction, and sports. A standard door is about 2 meters tall, and the average adult walking pace covers roughly 1 meter per step.

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

See all 15 length units in matrix view →

• Room dimensions and building measurements in Europe
• Track-and-field events (100 m, 200 m, 400 m sprint)
• Scientific papers and engineering drawings worldwide

• ✓1 metre ≈ 3.28 feet — multiply by 3.28 for a quick foot conversion.
• ✓The height of an average adult is 1.6 to 1.8 metres — useful for sanity-checking lengths.
• ✓For very small or very large quantities use prefixes: 1 km = 1000 m, 1 mm = 0.001 m.

• ✗Confusing square metres (area) with metres (length). A 20 m² room is not 20 m long.
• ✗Using 3.3 instead of 3.2808 when converting to feet — the error grows on long distances.
• ✗Writing "meter" when you mean "metre" in British English, or vice versa. Both are accepted but follow one convention per document.