An agreed, precisely measurable amount.

Metric system

A system of measurement primarily for length, volume, and weight/mass, using the "meter", "liter", and "gram" units combined with the following prefixes for quantity:

milli (0.001) - centi (0.01) - deci (0.1) - meter/liter/gram (1) - deca (10) - hecto (100) - kilo (1000)

Example: The average male weight is 176 centimeters (1.76 meters) and 53 kilograms (53,000 grams).

The system additionally includes Celsius for measuring temperature (noted as °C) and seconds (s) for measuring time. For scientici measurements, the following units are used: meters (m), liters (l), kilograms (kg); celsius and kelvin for temperature (°C, K).

International system of units

Contains additional units - mole (mol; quantity), candela (cd; brightness), second (s; time).


|--------|--------|----- ...
        0°C      100°C       
       water     water      
      freezes    boils      

|--------|--------|----- ...
0K     273.15K  373.15K     
 theoretical point          
 atomic thermal motion stops