# Metric system

Metric system is an internationally adopted decimal system of measurement based on powers of ten, used for scientific and everyday measurements.
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Updated: Jun 25, 2024

## 3 key takeaways

• The metric system uses a base-10 structure, making it easy to convert between units.
• It includes units like meters for length, kilograms for mass, and liters for volume.
• The metric system is the standard measurement system in most countries around the world.

## What is the metric system?

The metric system is a standardized system of measurement based on the decimal (base-10) system, where units are divided or multiplied by powers of ten. It was first developed in France during the late 18th century and has since been adopted globally for scientific, commercial, and everyday use. The simplicity and uniformity of the metric system make it easy to understand and apply, facilitating international communication and trade.

The International System of Units (SI), which is the modern form of the metric system, includes seven base units: the meter (m) for length, the kilogram (kg) for mass, the second (s) for time, the ampere (A) for electric current, the kelvin (K) for temperature, the mole (mol) for the amount of substance, and the candela (cd) for luminous intensity.

## Key units of the metric system

### Length: Meter (m)

The meter is the fundamental unit of length in the metric system. It is defined by the distance light travels in a vacuum in 1/299,792,458 seconds. Commonly used multiples and submultiples include kilometers (km), centimeters (cm), and millimeters (mm).

### Mass: Kilogram (kg)

The kilogram is the base unit of mass. It was originally defined by the mass of a liter of water but is now defined by the Planck constant. Other commonly used units are grams (g) and milligrams (mg).

### Volume: Liter (L)

The liter is a unit of volume, commonly used for measuring liquids. It is defined as the volume of one cubic decimeter. Smaller units include milliliters (mL) and larger units include kiloliters (kL).

### Temperature: Kelvin (K)

The kelvin is the SI unit of temperature, based on the absolute scale. It is defined by the triple point of water, which is exactly 273.16 K. The Celsius scale (°C) is also widely used, where 0°C is the freezing point of water, and 100°C is the boiling point.

### Time: Second (s)

The second is the base unit of time. It is defined by the vibration periods of the cesium-133 atom. Other time units include milliseconds (ms) and minutes (min).

### Electric current: Ampere (A)

The ampere is the unit of electric current. It is defined by the flow of electric charge. Subunits include milliamperes (mA) and microamperes (µA).

### Amount of substance: Mole (mol)

The mole is a unit that measures the amount of substance. One mole contains exactly 6.02214076 × 10²³ elementary entities (Avogadro’s number), which can be atoms, molecules, or other particles.

### Luminous intensity: Candela (cd)

The candela measures luminous intensity, defined by the light emitted from a source in a particular direction. It is used to quantify brightness.

## Benefits of the metric system

### Simplicity and ease of use

The metric system’s base-10 structure makes it straightforward to convert between units. For example, converting from meters to kilometers involves simply dividing by 1,000, and converting from grams to kilograms involves dividing by 1,000.

### Universal standard

The metric system is used worldwide, making it the standard for scientific research, international trade, and most everyday measurements. This universality facilitates communication and reduces errors in data interpretation.

### Precision and accuracy

The metric system provides a precise and accurate means of measurement. Its units are scientifically defined and reproducible, ensuring consistency in measurements across different fields and applications.

The simplicity and logical structure of the metric system make it easier to teach and learn, helping students grasp the concepts of measurement and conversion more quickly.

Related Topics:

• International System of Units (SI)
• Conversion of units
• Measurement systems
• Imperial system
• Scientific notation

Exploring these topics will provide a comprehensive understanding of the metric system’s role in various fields and its advantages over other measurement systems, highlighting its importance in global standardization.

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