mm

Some other associated conversions -
1 kilometre ( km ) = 1000 metre , 1 metre = 100 cm , 1 cm = 10 mm
1 mile = 5280 feet , 1 yard ( yd ) = 3 feet , 1 fathom = 6 feet , 1 chain = 66 feet
1 foot (ft.) = 12 inches (in.)

To convert decimal fractions of an inch to fractions of an inch.

Take the decimal fraction of feet and divide by 0.08333 (1/12th) and this will give you inches and decimals of an inch.
For example - 6.37 feet. Take the 0.37 feet and divide by 0.0833 = 4.44 inches
so for 6.37 ft. we can also say 6 ft.- 4.44 in.
Now take the 0.44 in. and round it down to 0.4 which is ⁴/₁₀"
We can now say 6.37' approximatly equals 6' - 4 ⁴/₁₀"

For fractions of an inch other than tenths, take the decimal remainder of inches and divide by:-
0.125 for the number of eighths
0.0625 for the number of sixteenths
0.03125 for the number of thirty-seconds
0.015625 for the number of sixty-fourths, and so on.

For example - 4.382 inches. For eighths, divide the remainder, 0.382 by 0.125 and the answer is 3.056 so the fraction is a bit over 3 eighths, therefore the answer ends up as approx. 4 ³/₈"

1 millimetre is about one twenty-fifth of an inch ( 1 in. = 25.4 mm )

Feet may be shown as ft. or ' and inches as in. or "