It is an anachronism ....
Most of the world has switched to the metric system now, even the US is supposed to use it, but still refuses.
The "Imperial" System is complicated.
1 foot = 12 inch
1 yard = 3 foot
1 mile = 1760 yard
and it uses weird fractions like 7/64 inch
while the metric system is more logical
1 mm = 1000 µm
1 m = 1000 mm
1 km = 1000 m
English.
There is no individual unit in the Metric system that is near one inch in the English system, I'm afraid.
An inch is such a measure.
a centimeter is closest
mil refers to 1/1000 th if it is in the english system then it would be 1 inch.
There are seven SI Base Units. These are:metre -distancekilogram -masssecond -timeampere -electric currentkelvin -thermodynamic temperaturecandela -luminous intensitymole -amount of substanceAll other SI units are called Derived Units.Read more: at the related link
The British Empire started using Imperial Units around 1825, which is the closest to the units that we still use today (inch, pound, foot, ton, mile, etc.). Before 1825 the British Empire was using English Units, which were very similar to the Imperial Unit, with more units of measurment in between. For example, you had the Digit (3/4 inch), the Finger (7/8 inch), the Hand (4 inches), the Nail (3 digits), the Palm (3 inches). And the inch itself was made up of 3 barleycorns. The barleycorn being the smallest of the English Units
The United States system of units is similar to the British imperial system. Both systems are derived from English units, a system which had evolved over the years before American independence, and which had its roots in Roman and Anglo-Saxon units. ~Wikipedia
39 inch
Inch
The English system is inch, foot, yard, mile for length. Mass (like weight) is ounce, pound, and ton. 12 inches in a foot 3 feet in a yard 1,760 yards in a mile 16 ounces in a pound 2000 pounds in a ton
The english system is the metric system. There is no difference.