In Brazil, practically all rulers sold have values in centimeters, one of the basic measurement units of the metric system. Even so, it is important to know how to interpret the numbers, especially when you have a ruler in another system (such as the imperial) or when it does not even have such values. Furthermore, it is also possible to use common office objects to determine the length of some items. Read this article to learn how to do all that, plus converting different units.

## Steps

### Method 1 of 4: Using a Ruler to Take Measurements

#### Step 1. Find the centimeter value on the ruler

Many rulers have several sets of numbers, which can be represented in the metric system. The side of the object has something like cm{displaystyle cm}

, a abreviatura de centímetros,, e/ou mm{displaystyle mm}

, de milímetros.

- Milímetros são a menor unidade métrica de quase qualquer régua. São representados pelas linhas mais curtas, que ficam entre os centímetros.
- A régua pode ter medidas em outro sistema de unidades, como o imperial (em polegadas), do outro lado.

#### Step 2. Understand the relationship between millimeters and centimeters

If you examine the ruler closely, you will see that each centimeter is divided into ten parts, represented by shorter lines. So remember: each mm is equal to 1/10 of a cm.

### In more mathematical terms: 1 mm = 0.1 cm

#### Step 3. Align the end of the object with the first centimeter line of the ruler

The tip of physical rulers is not always aligned with the beginning of the first centimeter. Be careful and make the necessary adjustments.

### Keep the ruler straight on the object you want to measure

#### Step 4. Measure the object in exact centimeters

Look at the other end of the object and identify the mark that is closest to it. That way you will determine its length.

- The object's length is determined by the point where its end reaches the ruler. For example, if the tip of an eraser is on the line with a 7, it is 7 cm long.
- If measuring to the nearest centimeter, find the closest line to the tip of the object itself. She will point out the ideal value. For example: the rubber can be between 7 and 8 centimeters. If it gets closer to the 7 line, say it's 7 x centimeters long.

#### Step 5. Measure the object at a value close to exact

Look at the last centimeter line the object passes through. Then count the number of millimeters until you reach the end of it. Each millimeter equals 1/10 of a centimeter; so, determine the length and add the value in cm and in tenths.

### For example, if the tip of an eraser is on the 1 mm line after 7 cm, it is 7, 1 cm long

### Method 2 of 4: Estimating the Length of an Item in Centimeters Using Objects

#### Step 1. Take some objects that are about 1 cm wide

If you don't have a ruler available and you need to estimate the length of something in centimeters, you can use anything that's the right width.

- The most common objects for this are pencils, pens or markers, which are about 1 cm wide.
- Other options are staples, five stacked CDs or DVDs, a regular notepad and the radius of a $0.50 coin.

#### Step 2. Place the object you are measuring on a sheet of paper

See if it fits and mark the first end with a pencil or pen.

### The paper must be clear for you to see the marks

#### Step 3. Place the object you are using to measure at the end of the other

Align one edge to the first edge of the item you want to calculate.

### For example, if you are using the width of a pencil to estimate in centimeters, place it at a perpendicular angle to the item being measured - so that the ends of the eraser and graphite are against what you are measuring. One side of the pencil should line up with the end of the other object

#### Step 4. Mark the other end of the object you are using to measure

Be careful not to dislodge anything and make a mark on the inside edge of the object with a pencil or pen.

#### Step 5. Change the position of the object you are using to measure

Reposition it so that its other end is over the mark you made earlier. Make one more appointment; this time, on the inside edge of the object.

### Leave the object you are using to measure well aligned with the side of the item when you change its position. The item you want to measure must stand still

#### Step 6. Repeat the process

Continue marking the inside edge of the object until you reach the tip, always making sure everything is aligned and marked.

#### Step 7. Count the spaces

When finished, lift the objects (which you used as a base and which you measured). Count the number of spaces between the markings to arrive at the estimated length in centimeters.

### Count spaces, not lines or marks

### Method 3 of 4: Converting Other Metric Units to Centimeters

#### Step 1. Convert millimeters to centimeters

Each cm is 10 mm. To convert, just divide the millimeter number by ten.

- For example: to convert 583 millimeters to centimeters, just calculate 58310=58, 3{displaystyle {frac {583}{10}}=58, 3}
. Portanto, 583 mm = 58, 3 cm.

#### Step 2. Convert meters to centimeters

Each m is 100 cm. To convert, simply multiply the number in meters by 100.

- For example: to convert 5.1 meters to centimeters, just calculate 5, 1×100=510{displaystyle 5, 1\times 100=510}
. Portanto, 5, 1 m = 510 cm.

#### Step 3. Convert kilometers to centimeters

Each km is 100 thousand cm. So, to make the conversion, just multiply the original value by 100 thousand.

- For example: to convert 2, 78 kilometers to centimeters, just calculate 2, 78×100,000=278,000{displaystyle 2, 78\times 100,000=278,000}
. Portanto, 2, 78 km = 278.000 cm.

### Método 4 de 4: Convertendo unidades de outros sistemas em centímetros

#### Step 1. Convert inches to centimeters

Each inch is approximately 2.54 centimeters. To convert, simply multiply the original value (in inches) by 2.54.

- For example: to convert 9.41 inches to centimeters, just calculate 9, 41×2, 54=23, 9{displaystyle 9, 41\times 2, 54=23, 9}
. Portanto, 9, 41 pol = 23, 9 cm.

#### Step 2. Convert feet to centimeters

Each foot is approximately 30, 48 centimeters. To convert, simply multiply the original number (in feet) by 30, 48.

- For example: to convert 7, 2 feet to centimeters, just calculate 7, 2×30, 48=219, 46{displaystyle 7, 2\times 30, 48=219, 46}
. Portanto, 7, 2 pés = 219, 46 cm.

#### Step 3. Convert yards to centimeters

Each yard contains three feet, and each foot contains 30, 48 cm. Therefore, the number of cm in a yard is triple: 91, 44. To convert, simply multiply the number by this value.

- For example: to convert 3.51 yards to cm, just calculate 3, 51×91, 44=320, 96{displaystyle 3, 51\times 91, 44=320, 96}
. dessa forma, 3, 51 jardas = 320, 96 cm.