9 Centimeters to Inches (9 cm to in)

Symbol

The Centimeter is represented by the symbol “cm.”

Description

Centimeter is a unit of length in the metric system which is also the International System of Units (SI). It was the base unit of length in the now deprecated CGS (centimeter-gram-second) system of units.

Centi is the SI prefix for a factor of 1/100.  A centimeter approximately corresponds to the average adult person's fingernail width. This unit is equal to one-hundredth of a meter, the base of the SI unit of length. So, a centimeter is equal to 1/100 meters. Though measurement units frequently choose SI prefixes for factors of 10^3, such as milli- and kilo-, for many physical values, however, the centimeter remains a practical unit of length for many everyday measurements. 

Centimeters can be changed to other SI units using prefix multipliers based on powers of ten. For example, a millimeter equals 1/10 centimeters. So, a centimeter is equivalent to 10 millimeters.

If you are converting cm to inch, then the calculation is different. One inch is equal to 2.54 centimeters. Therefore, one centimeter is equivalent to 0.393701 inches.

History

The term centimeter was first used in the late 1700s. The centimeter is a part of the metric system. The metric system of measurement is primarily credited to the French. The French government officially adopted this system on April 7, 1795.

Use

The centimeter as mentioned before is unit of length. It is more commonly used for dimensions for which meter measure is unrealistically large. 

Symbol

The inch is represented by the letters in or a double straight quotation mark (“). For example, 5 inches is written as 5 in or 5”. 

Description

Inch is one of the smaller units of length measurement in the British imperial and the United States customary system of measurement. This estimation is thought to have derived from the width of the human thumb. The word ‘inch’ was derived from the Roman word "uncia" (twelfth).

In the past, there have been multiple standards regarding the exact measurement of an inch. However, with the adoption of the international yard during the 1950s and 1960s, the inch has been based on the metric system and defined as exactly 25.4 mm.

So it is quite easy to convert centimeter to inch or in to cm. According to the international scales, there are 2.54 centimeters in an inch. So inversely, an inch is equivalent to 1/2.54 centimeters.

For inch to foot conversion, note that one foot is equal to 12 inches. So, while doing ft to in conversion just divide the inch digits by 12 since an inch is equivalent to 1/12 feet. For in to yard conversion, an inch is equivalent to 1/36 yard.

History

Inch was used in the Textus Roffensis in 1120. It is the only surviving manuscript from the Laws of Æthelberht (which dates to the early 7th century). It is the earliest known reference to the inch in England. 

King Edward II of England proclaimed in 1324 that one inch was equivalent to three barley grains put end to end lengthwise. But as the barley grains' size could not be fixed, there was a possibility of having error in standardizing inch by this defintion. Actually before the establishment of the international yard and pound, numerous definitions were used for inch.

In 1912, US and UK followed different definitions of inch measurement. Carl Edvard Johansson then reached a compromise. He produced gauge blocks with a nominal size of 25.4 mm that were accurate to within a few parts per million of both official standards. Because of the popularity of Johansson's blocks, several countries began using 25.4 mm as the inch between 1930 and 1964. It became known as the industrial inch. And this has since become the new official measurement of the inch. 

Use

Inch is mostly used in countries following the FPS (foot-pound-second) system of units. It is sometimes used for measuring small dimensions such as mobile display or electronic parts.