The modern metric system, also known as the International System of Units is based on a unit measure called the meter and the decimal system. Most of this discussion will focus on millimeters as used in desktop publishing.
NOTE: The spelling used most commonly in the United States is meter; however, both meter and metre are acceptable spellings in the US.
The Tens Have It
A meter is roughly equivalent to a yard. In inches it is about 39.37 inches compared to the 36 inches in a yard. Since yards and meters are a bit larger than the paper and publication sizes most desktop publishers deal with, we need to break it down further. Yards break down into feet and inches and then fractions of inches. Meters are a little easier once you grasp the basics. Notice how neatly they break down in multiples of 10.
m=Meter, dm=Decimeter, cm=Centimeter, mm=Millimeter
- 1 m = 10 dm = 100 cm = 1000 mm
- 1 dm = 10 cm = 100 mm
- 1 cm = 10 mm
- 1 mm = 1/10 of a cm
Moving from meters down to centimeters up to decimeters and back down to millimeters is just a matter of adding and subtracting zeros or dividing or multiplying by 10, 100, or 1000. However, beyond the math there is the matter of visualizing the metric world. Those of us who grew up with feet and inches can usually judge the length of a line or the dimensions of a book within an inch or less just by looking at it. We need a new frame of reference when moving to metric.
Visual Tricks
Metric paper sizes for typical desktop publishing applications are expressed in millimeters but how big or small is a millimeter? To help develop a visual frame of reference, use this exercise found in the U.S. Metric Association, Inc. FAQ:
«...the millimeter is a tiny unit that replaces fractions of inches. Its length is the size of the thickness of a dime. Each time you hear the word, millimeter, think: the thickness of a dime. If someone mentions an item is 10 millimeters long, just imagine how high a stack of 10 dimes would be to get an idea of that item's length.»
Other approximations that are useful in learning to visualize metric measurements are:
1 m
yardstick plus a stick of chalk
15 cm or 150 mm
Bic Pen with cap on
8 cm or 80 mm
length of a clothespin
3 cm or 30 mm
length of a small paperclip
25 mm
about 72 pts or 1 inch
2 cm or 20 mm
diameter of a Jefferson nickel
6 mm
about a quarter of an inch
Next > Learning to Use Metric Measures
Intermediate Tasks > Measurement Systems > Metric for Non-Metric Users
