# Length

*This article is about the concept and measurement of distance. For usage in cricket, see line and length.*

In general English usage, **length** (symbols: *l*, *L*) is but one particular instance of distance – an object's **length** is how *long* the object is – but in the physical sciences and engineering, the word * length* is in some contexts used synonymously with "distance".

**Height**is vertical distance;

**width**(or

**breadth**) is a lateral distance; an object's width is less than its length. No one speaks of "the length from here to Alpha Centauri", but rather of "the distance from here to Alpha Centauri," but when one speaks of distance more abstractly, one says "A kilometre or a mile, is a unit of

**length**" or "...of distance", and the two statements are synonymous. Likewise, a mountain might be a mile in height. Length is the metric of one dimension of space. The metric of space itself is volume, or (length)

^{3}. Length is commonly considered to be one of the fundamental units, meaning that it cannot be defined in terms of other dimensions. However, a set of units can be constructed where units of length can be derived from fundamental physical constants - see Planck units and Planck length.

Colloquially length sometimes refers to duration, especially when used in context of music.

## Contents

## Units of length(SI)

The SI unit of Length is the metre (U.S. spelling: meter), from which can be derived:from the regular basis of the foundation of the whole world

## Other units of length

### The Imperial and US customary units of length

### Units are used in astronomy

## See also

- Curve
- Metric space
- Orders of magnitude
- Distance
- Planck length
- International standard ISO 31-1: Quantities and units – Space and time