1. SI Measure m ent
The In ternatio nal System of Units, or SI, is t he stan dard system of measuremen t used by many scien tists. Using t he same stan dards of measuremen t makes it easier for scien tists to co mm u nicate wit h o ne an ot her.
SI works by co m bining prefixes an d base u nits. Each base u nit can be used wit h dif- feren t prefixes to define smaller an d larger quan tities. The table below lists co mm o n SI prefixes.
SI Prefixes
Prefix
Abbreviation
Factor
Example
kilo- k
1,000
kilogram, 1 kg = 1,000 g
hecto- h
100
hectoliter, 1 hL = 100 L
deka- da 10
dekameter, 1 dam = 10 m 1
meter, liter
deci- d
0.1
decigram, 1 dg = 0.1 g
centi- c
0.01
centimeter, 1 cm = 0.01 m
milli- m
0.001
milliliter, 1 mL = L
micro-
micrometer, 1 µm = m
SI Conversion Table
SI units
From SI to English
From English to SI
Length
kilometer (km) = 1,000 m
1 km = mi
1 mi = km
meter (m) = 100 cm
1 m = ft
1 ft = m
centimeter (cm) = 0.01 m
1 cm = in.
1 in. = cm
millimeter (mm) = m
1 mm = in.
micrometer (µm) = m
nanometer (nm) = m
Area
square kilometer (km2) = 100 hectares
1 km2 = mi2
1 mi2 = km2
hectare (ha) = 10,000 m2
1 ha = acres
1 acre = ha
square meter (m2) = 10,000 cm2
1 m2 = ft2
1 ft2 = m2
square centimeter (cm2) = 100 mm2
1 cm2 = in.2
1 in.2 = cm2
Volume
liter (L) = 1,000 mL = 1 dm3
1 L = fl qt
1 fl qt = L
milliliter (mL) = L = 1 cm 3
1 mL = fl oz
1 fl oz = mL
microliter (µL) = L
Mass
kilogram (kg) = 1,000 g
1 kg = lb
1 lb = kg
gram (g) = 1,000 mg
1 g = oz
1 oz = g
milligram (mg) = g
microgram (µg) = g