Inches to mm
About Inches
Inch is a commonly used unit of length or measurement in different systems, including the Imperial Units, English Units and US Customary Units. The size of an inch can vary from system to system.
One inch is equal to 1/36th of a yard and 1/12th of a foot. Also, 1 inch to mm is 25.4, while 1 inch to cm is 2.54. Inch is either written as ‘in’ or denoted by a double prime [“]. For instance, 10 inches can be written as 10 in or 10”.
This dominant unit of measurement is popularly used in the United States, United Kingdom, Canada, Japan, India and some other countries around the world.
The History of Inches
The word inch was initially borrowed from the Roman word ‘Uncia’, meaning twelfth in English. However, in other European languages, the name inch was taken from the word thumb. This was when no standard units of measurement existed and the lengths and widths of certain body parts, like finger, thumb and foot, were used to measure different areas.
The King of Scotland David I reportedly defined one Scottish inch as the width of an average man’s thumb at the base of his nail. On the other hand, King Edward II of England opined that one inch will be equal to “three grains of sound ripe barley taken out the middle of the ear and laid end to end in a line”.
Many such definitions of the inch were in use until the latest one was proposed and confirmed by different countries over the years. The definition of an inch was adopted in Canada in 1951, in the US in 1959, in Australia in 1961 and in UK in 1963. It stated that an inch is exactly 25.4 mm or 2.54 cm.
Here’s how inches can be defined based on one yard:
1 inch = 1/36 yard or 0.0278 yard
1 yard = 914.4 mm
Hence, 1 inch = 0.0278 x 914.4 = 25.4 mm
About Mm
A millimeter is a metric unit commonly used for measuring small spaces, objects and distances. It is a part of the International System of Units (SI units) and is equal to 1/1000th meter and 1/10th of a centimeter. This denotes that there are 1000 millimeters in one meter and 10 millimeters in 1 centimeter. The size of the thin wire used in paper clips is one millimeter.
This unit of measurement is widely used in engineering-related drawings and specifications. Hence, while most standard rulers have 1 mm graduations, the ones specifically used for engineering purposes also have 0.5 mm graduations.
The millimeter is widely used in other fields as well. For instance, in the field of medicine, a millimeter is used for measuring the size of tumors. The thickness of a paper sheet is also measured in millimeters. While an ordinary sheet of paper is about 0.07 mm to 0.18 mm thick, the one used for printing has a thickness of approximately 0.1 mm. Also, the width of a standard pen nib is 0.6 mm.
Convert inches to mm. Please provide values below to convert inch [in] to millimeter [mm], or vice versa.
Inch
Definition: An inch (symbol: in) is a unit of length in the imperial and US customary systems of measurement. An inch was defined to be equivalent to exactly 25.4 millimeters in 1959. There are 12 inches in a foot and 36 inches in a yard.
History/origin: The term "inch" was derived from the Latin unit "uncia" which equated to "one-twelfth" of a Roman foot.
There have been a number of different standards for the inch in the past, with the current definition being based on the international yard. One of the earliest definitions of the inch was based on barleycorns, where an inch was equal to the length of three grains of dry, round barley placed end-to-end. Another version of the inch is also believed to have been derived from the width of a human thumb, where the length was obtained from averaging the width of three thumbs: a small, a medium, and a large one.
Current use: The inch is mostly used in the United States, Canada, and the United Kingdom. It is also sometimes used in Japan (as well as other countries) in relation to electronic parts, like the size of display screens.
Millimeter
Definition: A millimeter (symbol: mm) is a unit of length in the International System of Units (SI). It is defined in terms of the meter, as 1/1000 of a meter, or the distance traveled by light in 1/299 792 458 000 of a second.
History/origin: The milli- prefix is one of many metric prefixes. It indicates one thousandth of the base unit, in this case the meter. The definition of the meter has changed over time, the current definition being based on the distance traveled by the speed of light in a given amount of time. The relationship between the meter and the millimeter is constant however. Prior to this definition, the meter was based on the length of a prototype meter bar. In 2019, the meter has been re-defined based on the changes made to the definition of a second.
How to Convert Inch to Millimeter
1 in = 25.4 mm
1 mm = 0.0393700787 in
Example: convert 15 in to mm:
15 in = 15 × 25.4 mm = 381 mm