Mainly three temperature scales are widely used. Out of them, the Fahrenheit (°F) temperature scale and Celsius (°C) temperature scale is widely used in science and is used practically everywhere. The Kelvin (K) scale is the international standard for measuring temperature in scientific applications.

In some technological specialties, a distinct absolute temperature scale, the Rankine scale (see William Rankine), is chosen over the Kelvin scale. The kelvin equals one Celsius degree, while the degree Rankine (°R) equals one Fahrenheit degree.