There are seven different fundamental quantities of measurement in the International System of Units (or SI from the French: Système international d'unité), or in layman's terms, the metric system.

These fundamental quantities in alphabetical order are:

A candela is a unit of luminous intensity with the symbol of Iv.

A kelvin is a unit of temperature with the symbol of K. Zero kelvins (0 K) is absolute zero or -273 degrees Celsius (°C) and the freezing point of water is 273K or 0°C, so the scale of 1K and 1°C is identical.

A kilogram is a unit of mass (not weight, as commonly assumed) with the symbol kg. A kilogram is an arbitrary measurement which is technically defined as the mass of a lump of platinum alloy in Paris, but can be rounded up to the mass of a liter of water as it is almost on identical.

A meter is a unit of distance with the symbol m. It was originally defined as fraction of the distance between the Earth's equator to the North Pole (before it was realized the Earth changes shape), then it was an arbitrary measurement of the distance between two marks on a stick in Paris and is now defined as the distance traveled by light in a vacuum in 1⁄299,792,458th of a second.

A mole is a unit of quantity or amount of a chemical substance. It has the symbol mol.

A second is a unit of time and has the symbol s. Originally defined as a fraction of the time the Earth takes to orbit the Sun, it is now defined as '...the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom'.

These fundamental quantities in alphabetical order are:

- Ampere
- Candela
- Kelvin
- Kilogram
- Meter
- Mole
- Second

A candela is a unit of luminous intensity with the symbol of Iv.

A kelvin is a unit of temperature with the symbol of K. Zero kelvins (0 K) is absolute zero or -273 degrees Celsius (°C) and the freezing point of water is 273K or 0°C, so the scale of 1K and 1°C is identical.

A kilogram is a unit of mass (not weight, as commonly assumed) with the symbol kg. A kilogram is an arbitrary measurement which is technically defined as the mass of a lump of platinum alloy in Paris, but can be rounded up to the mass of a liter of water as it is almost on identical.

A meter is a unit of distance with the symbol m. It was originally defined as fraction of the distance between the Earth's equator to the North Pole (before it was realized the Earth changes shape), then it was an arbitrary measurement of the distance between two marks on a stick in Paris and is now defined as the distance traveled by light in a vacuum in 1⁄299,792,458th of a second.

A mole is a unit of quantity or amount of a chemical substance. It has the symbol mol.

A second is a unit of time and has the symbol s. Originally defined as a fraction of the time the Earth takes to orbit the Sun, it is now defined as '...the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom'.