# System of Units – Basics

Units are measurement standards. System of units is classified into two categories: Fundamental units and Derived units.

Fundamental units are further subdivided into following types:

1. MKS - meter, kilogram, second
2. CGS - centimeter, grams, second
3. FPS - foot, pound, second
4. S.I - precise form of MKS, used internationally.

Derived units are units derived from fundamental. It is a set of fundamental units which are used to express some form. Derived units are either dimensionless or a product of fundamental units.

Example: Kg/m², ft/in², psi, etc.

## Fundamental Units

#### SI or MKS

• Length - millimeter; mm
• Mass - kilogram, kg
• Time - seconds; s
• Temperature - Kelvin, K
• Electric Current - Ampere; A

#### FPS system of units

• Length - foot; ft
• Mass - pound; lb
• Time - seconds; s
• Temperature - Fahrenheit; F
• Electric Current - Ampere; A

#### CGS

• Length - centimeter; cm
• Mass - gram, g
• Time - seconds; s
• Temperature - Celsius, C
• Electric Current - Ampere; A