The measurement of the distance of something from side to side.
In math, width is the measurement of how wide something is from one side to the other. It is usually measured at a right angle (90°) to the length.
For example:
- The width of a book is the shorter side when it’s lying flat.
- A rectangle has both a length and a width.
- The width of a classroom is the distance from one wall to the opposite wall.
Width is one of the basic dimensions we use to describe shapes and objects. In two-dimensional shapes like rectangles, we measure length and width. In three-dimensional shapes, width is one of the measurements used to calculate volume.
We use width when:
- Measuring rooms, desks, or screens
- Finding the area of a rectangle (Area = length × width)
- Describing the size of objects
When Do Students Learn About Width?
Students begin learning about width when they explore measurement and basic geometry.
Grades K–2 – Comparing Length and Width
Students compare objects and describe which is longer or wider using everyday language.
Grades 3–5 – Measuring Width
Students measure width using rulers and apply it in area and perimeter problems.
