Length (path) conversion

The unit of length is the meter. The meter is one of the seven base units of the SI unit system. All other units are derived from the base units.
In the 18th century the meter was defined as one ten-millionth part of a quadrant of the earth's meridian. The part of the meridian was selected from Barcelona to Dunkirk.

1799 this natural measure was eventually replaced by a scale of platinum and 1889 of platinum-iridium ( "standard meter" in Paris).

Since 1983 the length of 1 metre is determined as the distance which puts back the light in the vacuum during the duration of 1/299792458 seconds.

In Great Britain (UK) and in the United States of America (US)  inch, feet, yard and miles are common:
1 inch = 1/12 feet= 1/36 yard
1 inch = 25,4 mm
1 feet = 304,8 mm
1 yard = 914,4 mm
1 mile = 1,609 km = 1760 yards

The inch actually belongs to the old German unit system "line, inch, foot, ulna, fathom, rod, mile". 26,088mm would correspond with 1 Zoll according to old German system.
The following equal was determined in the conversion boards according to DIN 4890, 4892 and 4893(February 1935):

1 inch = 25,400000 mm.

1 nautical mile (sea mile) is 1,852 km.

Metrical units

UK and US units

1 Millimeter (mm)

0,03937 inch (in.)

1 Meter (m)

39,37 inch (in.) = 3,28083 feet (ft.) = 1,0936 yard

1 Kilometer (km)

3280,83 feet (ft.) = 1093,61 yard = 0,62137 miles

UK and US units

Metrical units

1 mil

1/1000 inch = 0,0254 Millimeter

1 inch (in.)

25,400 Millimeter (mm)

1 feet (ft.)

304,8 Millimeter (mm)

1 yard

0,9144 Meter (m)

1 mile (statute)

1,60934 Kilometer (km)

1 mile (nautic)

1,852 Kilometer (km)

Other units of length

1 geographical mile corresponds with 1/15 equator degrees = 7.420 kilometres.

1 light year = 9.463 billions kilometre = 63280 astronomical units.

1 astronomical unity is the middle distance the earth sun.

Further there is a unit of length for yarns in GB  "lea" or "lay" and "hank".

This unit is however different for linen and cotton:
1 lea = 300 yd = 274,3 m for linen (engl. spool)
1 lea = 80 yd = 73,15 m for cotton (short spool)
1 lea = 120 yd = 109,7 m for cotton (long spool)

The hank is different depending on material and region :
1 hank = 7 leas = 840 yd = 768 m for cotton
1 hank = 10 leas = 3.000 yd = 2.740 m for linen in England
1 hank = 12 leas = 3.600 yd = 3.290 m for linen in Ireland and Scotland
1 hank = 7 leas = 560 yd = 512 m for wool
1 hank = 2.496 threads = 3.328 yd = 3.040 m for twisted silk