The Metric System

from Industry Week, 1981 November 30

• Used in nearly every country in the world, the Metric System was devised by French scientists in the late 18th century. The goal of this effort was to produce a system that used the decimal system rather than fractions as well as a single unified system that could be used throughout the entire world.

Quantity measured Unit Symbol Relationship

Length, width,distance, thickness,girth, etc.

millimeter mm 10 mm = 1 cm

centimeter cm 100 cm = 1 m

meter m      

kilometer km 1 km = 1000 m

Mass(“weight”)*

milligram mg 1000 mg = 1 g

gram g      

kilogram kg 1 kg = 1000 g

metric ton t 1 t = 1000 kg

Time second s      

Temperature degree Celsius °C      

Area

square meter m²      

hectare ha 1 ha = 10 000 m²

square kilometer km² 1 km² = 100 ha

Volume

milliliter mL 1000 mL = 1 L

cubic centimeter cm³ 1 cm³ = 1 mL

liter L 1000 L = 1 m³

cubic meter m³

Speed, velocitymeter per second m/s      

kilometer per hour km/h 1 km/h = 0.278 m/s

Density kilogram per cubic meter kg/m³      

Force newton N      

Pressure, stress kilopascal kPa      

Power

watt W      

kilowatt kW 1 kW = 1000 W

Energy

kilojoule kJ      

megajoule MJ 1 MJ = 1000 kJ

kilowatt hour kW·h 1 kW·h = 3.6 MJ

Electric currentampere A    

Quantity measured Unit Symbol Relationship

T tera 1012 1 000 000 000 000 trillion

   G giga 109 1 000 000 000 billion

   M mega 106 1 000 000 million

   k kilo 103 1 000 thousand

   h hecto*   102 100   hundred

   da deka* 101 10   ten

100 1 one

   d deci* 101 0.1   tenth

   c centi* 102 0.01   hundredth

   m milli 103 0.001 thousandth

   µ micro 106 0.000 001 millionth

   n nano 109 0.000 000 001 billionth

   p pico 1012 0.000 000 000 001 trillionth

Prefixes

Converting with the Metric System

• When converting within the metric system it is simply a measure of moving the decimal in the appropriate direction.

Converting with the Metric System

• King Henry Drinks Milk During Castle Meetings

• Kilo Hecto Deca Meter Deci Centi Milli

• 1000 100 10 1 .1 .01 .001

• 1000 m = ______ km

• .001 hg = ______ dg

• 42.7 L = _____ cL

Things to remember

1. The short forms for metric units are called symbols, NOT abbreviations

2. Metric symbols never end with a period unless they are the last word in a sentence.

• RIGHT: 20 mm, 10 kg• WRONG: 20 mm., 10 kg.

3. Metric symbols should be preceded by digits and a space must separate the digits from the symbols

• RIGHT: the box was 2 m wide• WRONG: the box was 2m wide

Things to remember

4. Symbols are always written in the singular form

• RIGHT: 500 hL, 43 kg• WRONG: 500 hLs, 43 kgs• BUT: It is correct to pluralize the written out metric

unit names: 500 hectoliters, 43 kilograms5. The compound symbols must be written out

with the appropriate mathematical sign included

• RIGHT: 30 km/h, 12 cm/s• WRONG: 30 kmph, 30 kph (do NOT use a p to

symbolize “per”)• BUT: It is ok to write out “kilometers per hour”

Things to remember

6. The meaning of a metric symbol is different depending on if it is lowercase or capitalized

• mm is millimeters (1/1000 meters)• Mm is Megameters (1 million meters)