persquaremeter

Per square meter is a rate denoting a quantity divided by the area of one square meter. In formal terms it is a derived unit expressed as X per m^2, or equivalently a quantity with units X divided by m^2; the dimension is m^-2.

Areal density is the most common usage, expressed in units such as kg/m^2 or g/m^2; in the paper and textile industries it is also described as areal weight or areal density. For example, an 80 g/m^2 sheet of paper has an areal density of 80 g/m^2.

In energy and lighting, irradiance or flux density uses W/m^2; luminous irradiance is measured in lux, which is lm/m^2. These describe how much energy or light arrives on a surface per unit area.

In real estate and some manufacturing contexts, price or cost per square meter is common, with units like currency per m^2. This facilitates comparison across properties and products and helps compute total cost by multiplying by area.

The concept is widely used in science and industry, and the term per square meter is typically written with a space (per square meter) or abbreviated as m^-2 when used alone in equations. Related terms include areal density, areal weight, and various specific per-area units such as W/m^2 and lux.