1 inch: how many metres, centimetres, millimetres is it?

‘Give him an inch and he’ll take a mile’, says a popular phrase about ingrateful, greedy people. In the figurative sense, an inch is a small amount or quantity of something; and how long is it, actually?

An inch is one of the Imperial Units of length (also customarily used in the USA and Canada), equal to 0.0254m or 2.54cm or 25.4mm in metric [SI] units.

Originally, an inch had been the length of a person’s thumb. It was first standardised in the 14th century by King Edward II of England as equal to three barleycorns. In 1959, a treaty called International Yard and Pound Agreement was signed and it was agreed that the inch would be equal to 2.54cm in metric system.

INCH	Metric	0.0254 m	2.54 cm	25.4 mm
INCH	Imperial	¹/¹²foot	¹/₃₆yard

An inch is abbreviated to ‘in’ or [“], as in, e.g.: She’s 5’6” tall: She’s 5 feet and 6 inches tall.

Did you know?

The idea of an inch originated from the Latin word uncia, meaning a twelfth part of something (in a sense that an inch is one-twelfth of a foot). It had been spelled ynce in the Old English and later unche until the modern spelling emerged around the 14th century.

Interestingly, “inch” is a cognate of “ounce”, which also stems from the Latin “uncia”. It was adopted into Old English as ynce, too. In case of the ounce, it was one-twelfth of a Roman pound.

An inch has made its way into the English history and, consequently, it made an impact on the language, too. There are many idioms including the word inch. How many of them can you list?