# Steel Rule

```Reading a Ruler
in
Centimeters
and
inches
By: E E E Yassin
• Get a metric ruler. A metric ruler is based on the International System of
Units (SI), sometimes called the metric system, and is divided into either
millimeters or centimeters instead of inches. Rulers are often 30
centimeters long, which are designated by large numbers on the ruler.
Between each centimeter (cm) mark, there should be 10 smaller marks
called millimeters (mm).Make sure you read the ruler from left to right. If
you are measuring an object, align it with the left side of the zero mark on
the ruler. The left side of the line where the object ends will be its
measurement in centimeters. This way the line thickness will not affect the
measurement.
• Unlike with the English ruler, the measurements for the metric ruler are
written in decimals instead of fractions. For example, 1/2 a centimeter is
written as 0.5 cm.
• Learn the centimeter marks. The large numbers next to the longest lines
on the ruler denote the centimeter marks. A metric ruler has 30 of these
marks.
• For example, place the bottom of a crayon on the far left side of the ruler
to measure it. Note where the tip falls. If the crayon ends directly on the
long line next to the large number 14, your crayon is exactly 14cm long.
• Learn the 1/2 of a centimeter marks. Halfway between each centimeter,
there is a slightly shorter line that denotes 1/2 of a centimeter, or 0.5cm.
There are a total of 60 of these marks on a 30 cm ruler.
• For example, you measure a button and the edge ends on the fifth line
right between the 1 and 2 centimeter marks. Your button is 1.5cm long.
• For example, to measure 0.6 cm, count one thick line (5 mm) and one thin
line (1 mm).
• Learn the millimeter marks. Between each 0.5cm line, there are four
additional lines that denote the millimeter marks. There are a total of
10 lines per centimeter, with the 0.5cm line acting as the 5 millimeter
mark, making each centimeter 10mm long. There are 300 millimeter
marks on a 30 cm ruler.
• For example, if you measure a piece of paper and it ends on the 7th
mark between the 24 and 25 centimeter mark, it means your object is
247mm, or 24.7cm, long.
• Get an inch ruler. You'll know it's an inch ruler because it will have 12
lines that denote inches on the ruler. 12 inches equals 1 foot
(0.305 m). Each foot is broken down into inches.
• Each inch is broken down into 15 smaller marks, equaling 16 marks in
total for each inch on the ruler.
• The longer the line on the surface of the ruler, the bigger the
measurement is. Ranging from 1 inch to 1/16 of an inch, the lines
decrease in size as the unit of measurement does.
• Make sure you read the ruler from left to right. If you are measuring
something, align it with the left side of the zero mark on the ruler.
• The left side of the line where the object ends will be its
measurement in inches.
• Learn the inch marks. A ruler is made up of 12 inch marks. These are
typically the numbered marks on the ruler and are denoted by the
longest lines on the ruler.
• For example, if you need to measure a nail, place one end directly on
the left side of the ruler.
• If it ends directly above the long line next to the large number 5, then
the nail is 5 inches long.
• Some rulers will also denote 1/2 inches with numbers, so make sure
you are using the largest numbers with the longest lines as your inch
markers.
• Learn the 1/2 inch marks. The 1/2 inch marks will be the second
longest lines on the ruler, half as long as the inch marks. Each 1/2 inch
mark will come midway between each inch number because it is half
of an inch.
• This means that marks directly between the 0 and 1 inch, 1 and 2
inches, 2 and 3 inches, and so on across the ruler, are the 1/2 inch
marks. In total, there are 24 of these marks on a 12 inch ruler.
• For example, place the ruler against a pencil with the eraser at the far
left of the ruler. Mark where the tip of the pencil lead ends on the
ruler. If the pencil point ends at the shorter line halfway between the
4 and 5 inches marks, then your pencil is 4 and 1/2 inches long.
• Learn the 1/4 of an inch marks. Halfway in between each 1/2 inch
line, there will be a smaller line that denotes a 1/4 of an inch. In the
first inch, these marks will mark 1/4, 1/2, 3/4, and 1 inch.
• Although the 1/2 inch and 1 inch marks have their own lines, they are
still part of the 1/4 of an inch measurements because 2/4 of an inch
equals half an inch and 4/4 of an inch equals 1 inch. There are a total
of 48 of these marks on a 12 inch ruler.
• For example, if you measure a carrot and the tip falls on the line
halfway between the 6 1/2 and 7 inch lines, the carrot is 6 and 3/4
inches long.
• Learn the 1/8 of an inch marks. The 1/8 of an inch marks are the
smaller marks found directly in between the 1/4 of an inch marks on
the ruler. Between 0 and 1 inch, there are marks that denote 1/8, 1/4
(or 2/8), 3/8, 1/2 (or 4/8), 5/8, 6/8 (or 3/4), 7/8, and 1 (or 8/8) of an
inch. In total, there are 96 of these marks on a 12 inch ruler.
• For example, you measure a piece of fabric and the edge falls on the
6th line after the 4 inch mark, which is directly in between the 1/4 of
an inch mark and the 1/2 inch mark. This means that your fabric is 4
and 3/8 inches long
• Learn the 1/16 of an inch marks. The small lines halfway between each
1/8 of an inch denote 1/16 of an inch. These are also the smallest lines on
the ruler. The very first line on the left hand side of the ruler is the 1/16 of
an inch mark. Between 0 and 1 inch, there are marks that denote 1/16,
2/16 (or 1/8), 3/16, 4/16 (or 1/4), 5/16, 6/16 (or 3/8), 7/16, 8/16 (or 1/2),
9/16, 10/16 (or 5/8), 11/16, 12/16 (3/4), 13/16, 14/16 (or 7/8), 15/16,
16/16 (or 1) of an inch. There are a total of 192 of these lines on the ruler.
• For example, you measure a flower stem and the end of the stem falls on
the 11th line after the 5 inch mark. The flower stem is 5 and 11/16 inches
long.
• Not every ruler will have the 1/16 inch mark. If you plan on measuring
things that are small or you need to be extremely accurate, make sure the
ruler you use has these marks.
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