This table converts fractional 16ths of an inch into decimal inches and centimeters.
inches centimeters 1/16 0.0625 0.15875 1/8 0.125 0.3175 3/16 0.1875 0.47625 1/4 0.25 0.635 5/16 0.3125 0.79375 3/8 0.375 0.9525 7/16 0.4375 1.11125 1/2 0.5 1.27 9/16 0.5625 1.42875 5/8 0.625 1.5875 11/16 0.6875 1.74625 3/4 0.75 1.905 13/16 0.8125 2.06375 7/8 0.875 2.2225 15/16 0.9375 2.38125
Note that the equivalents in centimeters are exact, as one inch is 2.54 centimeters long. In the U.S., before 1964, it was instead the case that a meter was exactly 39.37 inches long, making the inch slightly larger than 2.54 centimeters; and in the British Commonwealth, the inch was slightly smaller than 2.54 centimeters, being defined on the basis of an independent physical standard.
If we're dealing with conversions between the English and metric units of length, a handy conversion chart such as that shown at right may be useful. It also embraces conversions from the height of horses, expressed in hands, and from a cubit of 18 inches in length.
In a cubit, four digits (each 3/4 inch long) make a span (three inches) and six spans make a cubit. In addition to the span being based on the width of a finger, and matching the spaces between the keys on a typewriter or computer keyboard, the cubit is based on the distance between the elbow and the tips of the fingers, as this diagram illustrates:
It also illustrates the existence, in ancient Egypt, of a royal cubit of seven spans in length, which figured in the construction of the Great Pyramid, accounting for the seeming appearance of the mathematical constant pi in its design, when what happened was that its approximation 3 1/7, closer to the one actually in use in Egypt in those days, simply appeared by a coincidence.
As typewriters typically print with six lines to the inch, another group of fractions of an inch is often used. Here, even the decimal inches usually cannot be exact
inches centimeters 1/6 0.1666667 0.4233333 1/3 0.3333333 0.8466667 1/2 0.5 1.27 2/3 0.6666667 1.6933333 5/6 0.8333333 2.1166667
The topic of units of measurement go in many directions, and so the discussion continues on several other pages.