| Name of unit
| Symbol
| Relation to SI units
|
| Length, l
|
| metre ( SI base unit) | m
| ≡ m
|
| Fermi | fm
| ≡ 10-15 m = 1 fm
|
| x unit; siegbahn | xu
| ≈ 1.0021×10-13 m
|
| stigma |
| ≡ 1×10-12 m = 1 pm
|
| Bohr radius | a0; b
| ≡ fine structure constant/(4π R) ≈ 5.291 772 083×10-11 ± 19×10-20 m
|
| atomic unit of length | au
| ≡ a0 ≈ 5.291 772 083×10-11 ± 19×10-20 m
|
| ångström | Å
| ≡ 10-10m = 0.1 nm
|
| micron | μ
| ≡ 10-6m = 1 μm
|
| twip | twp
| ≡ 1/1440 in ≈ 1.763 889×10-5 m
|
| mil; thou | mil
| ≡ 10-3 in = 2.54×10-5 m
|
| mickey |
| ≡ 1/200 in = 1.27×10-4 m
|
| calibre | cal
| ≡ 1/100 in = 0.254 mm
|
| point ( ATA ) | pt
| ≡ 0.013837 in = 0.351 459 8 mm
|
| point ( PostScriptPostScript (PS is a page description language used primarily in the electronic and desktop publishing areas. History The concepts of the PostScript language were seeded in 1976 when John Warnock was working at Evans and Sutherland, a famous computer graph) | pt
| ≡ 1/72 in ≈ 0.352 778 mm
|
| point (metric) | pt
| ≡ 3/8 mm = 0.375 mm
|
| point (Didot; European) | pt
| ≡ 0.376 065 mm
|
| line | ln
| ≡ 1/12 in ≈ 2.116 667 mm
|
| line (Paris) ["ligne"] | l
| ≡ 1/12 p = 1/443.296 m ≈ 2.255 829 mm
|
| line (Quebec) ["ligne"] | l (Qc)
| ≡ 1/12 p (Qc) = 2.255 837 5 mm
|
| barley corn |
| ≡ 1/3 in ≈ 8.466 667 mm
|
| finger |
| ≡ 7/8 in = 22.225 mm
|
| inchAn inch is an Imperial unit of length. Sweden also briefly had a "decimal inch" based on the metric system: see below for more. According to some sources, the inch was originally defined informally as the distance between the tip of the thumb and the firs | in
| ≡ 1/36 yd = 25.4 mm
|
| U.S. survey inch | in
| ≡ 1/12 U.S. survey foot = 100/3937 m ≈ 25.400051 mm
|
| inch (Paris) ["pouce"] | p
| ≡ 1/12 P = 1/(36 + 11.296/12) m ≈ 27.069 949 mm
|
| inch (Quebec) ["pouce"] | p (Qc)
| ≡ 1/12 P (Qc) = 27.070 05 mm
|
| stick |
| ≡ 2 in = 50.8 mm
|
| nail (cloth) |
| ≡ 2 1/4 in = 57.15 mm
|
| palm |
| ≡ 3 in = 76.2 mm
|
| hand |
| ≡ 4 in = 0.1016 m
|
| finger (cloth) |
| ≡ 4 1/2 in = 0.1143 m
|
| span |
| ≡ 6 in = 0.1524 m
|
| link (Gunter's) | lnk
| ≡ 66/100 ft = 0.201 168 m
|
| span (cloth) |
| ≡ 9 in = 0.2286 m
|
| quarter |
| ≡ 1/4 yd = 0.2286 m
|
| link (Ramden's; Engineer's) | lnk
| ≡ 1 ft = 0.3048 m
|
| footA foot is a non- SI unit of distance or length. The popular belief is that original standard was the length of a man's foot. The average foot length is about 240 mm (9. 4 in) for current Europeans. About 996 of 1000 British men have a foot that is less th (Clarke's; Cape) | ft (Cla)
| ≈ 0.304 797 265 4 m
|
| footA foot is a non- SI unit of distance or length. The popular belief is that original standard was the length of a man's foot. The average foot length is about 240 mm (9. 4 in) for current Europeans. About 996 of 1000 British men have a foot that is less th (Sear's) | ft (Sear)
| ≈ 0.304 799 47 m
|
| footA foot is a non- SI unit of distance or length. The popular belief is that original standard was the length of a man's foot. The average foot length is about 240 mm (9. 4 in) for current Europeans. About 996 of 1000 British men have a foot that is less th (Indian) | ft Ind
| ≈ 0.304 799 514 m
|
| footA foot is a non- SI unit of distance or length. The popular belief is that original standard was the length of a man's foot. The average foot length is about 240 mm (9. 4 in) for current Europeans. About 996 of 1000 British men have a foot that is less th (Benoît) | ft (Ben)
| ≈ 0.304 799 735 m
|
| footA foot is a non- SI unit of distance or length. The popular belief is that original standard was the length of a man's foot. The average foot length is about 240 mm (9. 4 in) for current Europeans. About 996 of 1000 British men have a foot that is less th | ft
| ≡ 12 in = 0.3048 m
|
| footA foot is a non- SI unit of distance or length. The popular belief is that original standard was the length of a man's foot. The average foot length is about 240 mm (9. 4 in) for current Europeans. About 996 of 1000 British men have a foot that is less th (American; U.S. Survey) | ft (US)
| ≡ 1200/3937 m ≈ 0.304 800 610 m
|
| footA foot is a non- SI unit of distance or length. The popular belief is that original standard was the length of a man's foot. The average foot length is about 240 mm (9. 4 in) for current Europeans. About 996 of 1000 British men have a foot that is less th (Paris) ["pied"] | P
| ≡ 1/(3 + 11.296/144) m ≈ 0.324 839 385 m
|
| foot (Quebec) ["pied"] | P (Qc)
| ≡ 1.06575 ft = 0.324 840 6 m
|
| cubit |
| ≡ 18 in = 0.4572 m
|
| pace |
| ≡ 2 1/2 ft = 0.762 m
|
| yard | yd
| ≡ 3 ft = 0.9144 m
|
| ell | ell
| ≡ 45 in = 1.143 m
|
| fathom | fm
| ≡ 6 ft = 1.8288 m
(sometimes ≡ 1/1000 NM = 1.852 m)
|
| rod; pole; perch | rd
| ≡ 16 1/2 ft = 5.0292 m
|
| rope | rope
| ≡ 20 ft = 6.096 m
|
| chain (Gunter's) | ch
| ≡ 66 ft = 20.1168 m
|
| chain (Ramden's; Engineer's) | ch
| ≡ 100 ft = 30.48 m
|
| arpent (Paris) | arp
| ≡ 180 P = 25 920/443.296 m ≈ 58.471 089 m
|
| arpent (Quebec) | arp (Qc)
| ≡ 180 P (Qc) = 58.471 308 m
|
| cable length (International) |
| ≡ 1/10 NM = 185.2 m
|
| cable length (Imperial) |
| ≡ 608 ft = 185.3184 m
|
| furlong | fur
| ≡ 660 ft = 201.168 m
|
| cable length (U.S.) |
| ≡ 720 ft = 219.456 m
|
| mile | mi
| ≡ 1760 yd = 5280 ft = 1609.344 m
|
| mile (American; Statute; U.S. Survey) | mi
| ≡ 5280 ft (US) = 5280×1200/3937 m ≈ 1609.347 219 m
|
| nautical mile | NM; nm
| ≡ 1852 m
|
| nautical mile (Admiralty) | NM (Adm); nm (Adm)
| ≡ 6080 ft = 1853.184 m
|
| geographical mile | mi
| ≡ 6082 ft = 1853.7936 m
|
| telegraph mile | mi
| ≡ 6087 ft = 1855.3176 m
|
| league | lea
| ≡ 3 mi = 4828.032 m
|
| statute league | lea
| ≡ 3 mi (US) ≈ 4828.041 656 m
|
| nautical league | NL; nl
| ≡ 3 NM = 5556 m
|
| light-second |
| ≡ 2.997 924 58×108 m
|
| light-minute |
| ≡ 60 light-seconds = 1.798 754 748×1010 m
|
| astronomical unit | AU
| = 149 597 870.691 ± 0.030 km
|
| spat | S
| ≡ 1012 m = 1 Tm
|
| light-hour |
| ≡ 60 light-minutes = 1.079 252 848 8×1012 m
|
| light-day |
| ≡ 24 light-hours = 2.590 206 837 12×1013 m
|
| light-year | l.y.
| ≡ c0×86 400×365.25
= 9.460 730 472 580 8×1015 m
|
| parsec | pc
| ≈ 180×60×60/π AU
≈ 206 264.806 25 AU
=
3.261 563 776 9 ± 6×10-10 light-years
= 3.085 677 581 3×1016 ± 6×106 m
|
