# Metric System

The Metric System, Abbreviations, and Conversions

for Common Units of Measure

On Line Unit Converter: http://www.easyunitconverter.com/

[ Table of Contents ]

| Rules for Use of Abbreviations | The Metric System |

| Length and Distance | Volume | Liquid Volumes | Mass | Area | Temperature | Pressure | | Humidity | Concentration | Salinity | pH | Time |

This page presents the most common abbreviations you will use in general biology, especially those for units of measure.

General Rules for Abbreviating Units of Measure

Always abbreviate units when reporting numerical information. Unless otherwise noted, singular and plural units are abbreviated the same. Percent is not abbreviated, but is represented by the familiar "%" symbol. Always put a space between the number and unit, e.g., 203.65 m, 457 um pH: The proper method for reporting pH is to place the unit before the number (pH 7); never insert the word "of" between the unit and number and avoid splitting the unit and number within a sentence - they should always go together. When do you abbreviate units vs. spelling out the unit(s) as word(s)? abbreviate units when you are reporting a numerical value:

"The maximum depth achieved by the ROV was 124 m approximately 2.3 km due south of Pt. Lobos."

spell out the unit as a word when using it in a non-numerical context, e.g., "All measurements were made in millimeters unless otherwise indicated."

When starting a sentence with a number and unit, both must be spelled out as words (this is something to avoid, if possible), e.g., "One thousand six hundred and eighty-seven kilograms of ground beef were randomly sampled and tested for E.coli contaminants between 21 August and 21 November, 1995."

The Metric System

The Metric System of measurement is the standard used by most scientific disciplines. The system is based upon measures of distance (in meters), volume (in liters), and mass (in grams). Scales of measurements increase or decrease as multiples of ten which facilitates expression of measurement values using the decimal system. The table below shows the most common prefixes and their relative magnitudes. Note that web browsers do not support use of superscripts and subscripts very well, so the notation 10^2 means "10 to the power of 2, or 10 squared". Similarly, the notation 10-2 should be read as "10 to the power of -2".

PrefixScientific Notation Decimal equivalents Example Units kilo- (k) = 10^3 = 1000kilogram (kg);

kilometer (km)

centi- (c) = 10-2 = 0.01centimeter (cm)

milli- (m) = 10-3 = 0.001milligram (mg);

millimeter (mm)

micro- (u) = 10-6 = 0.000001microgram (ug)

microliter (uL)

nano- (n) = 10-9 = 0.000000001nanogram (ng)

nanoamperes (nA)

pico- (p) = 10-12 = 0.000000000001picogram (pg)

picoamperes (pA)

Conversions

Units of Distance and Length

Metric Equivalents

1 km = 1000 m; 1 m = 100 cm = 1000 mm = 10^6 um = 10^9 nm

Metric Unit

multiplied by

= English Unit

millimeters

centimeters

centimeters

meters

meters

meters

kilometers

kilometers

0.0394

0.394

0.0328

39.4

3.28

1.1

3,281

0.621

inches (in)

inches

feet (ft)

inches

feet

yards (yd)

feet

miles (mi)

English Equivalents

1 mi = 1,760 yd = 5,281 ft; 1 yd = 3 ft = 36 in

English Unit

multiplied by

= Metric Unit

inches (in)

inches

inches

feet (ft)

yards (yd)

yards

miles (mi)

25.4

2.54

0.254

30.48

91.44

0.9144

1.609

millimeters

centimeters

meters

centimeters

centimeters

meters

kilometers

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Units of Mass

Metric Equivalents

1 mt (metric ton) = 1000 kg = 2,205 lb

1 kg = 1000 g = 2.205 lb = 35.2802 oz

1 g = 1000 mg = 10^6 ng = 10^9 pg

Metric Unit

Multiplied by

= English Unit

gram (g)

0.035

ounces (oz)

kilogram (kg)

2.2

pounds (lb)

metric ton (mt)

1.102

ton (t)

English Equivalents

1 ton = 2000 lb = 907.2 kg or 0.9072 mt

1 lb = 16 oz = 0.4536 kg = 453.6 g

English...

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