The best replacement for metric units is english units.

The best alternatives to metric units are rated as following:
★★★★★  english units
★★★  imperial
★★  imperial units
★  customary units
★  english
★  us units
★  si units
★  standard units
  si

Your alternative for metric units is not listed? Suggest!
Speaking about metric units, one probably shouldn't forget about length.

Other search terms related to metric units and their ratings are:
★★★★★ length
You have in mind a companion for metric units and it is not yet here? Propose!



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