it's not as bad as people say it is (but it is still pretty bad)
the chart: https://upload.wikimedia.org/wikipedia/commons/9/9e/English_Length_Units_Graph.svg
NIST handbook appendix C: https://www.nist.gov/system/files/documents/2019/11/05/appc-20-hb44_final.pdf
Revised Unit Conversion Factors: https://www.nist.gov/pml/us-surveyfoot/revised-unit-conversion-factors
Weights and Measures Act 1985 Schedule 1: https://www.legislation.gov.uk/ukpga/1985/72/schedule/1
see also:
https://en.wikipedia.org/wiki/Fahrenheit#History
https://en.wikipedia.org/wiki/Obsolete_Russian_units_of_measurement
https://en.wikipedia.org/wiki/Chi_(unit%29
http://patreon.com/hbmmaster
http://conlangcritic.bandcamp.com
http://seximal.net
http://twitter.com/hbmmaster
http://janmisali.tumblr.com