Going from Khmer to Cantonese (粡θͺ) has a composite linguistic distance of 71% (heuristic estimate). Below is the dimension-by-dimension breakdown.
Shared vocabulary, cognates, and loanwords.
Morphology, syntax, word order, cases.
Shared sounds and phoneme inventory.
Khmer β Chinese
Austroasiatic β Sino-Tibetan
The 5 languages with the lowest linguistic distance from Khmer:
A quick 3-question check between Khmer and Cantonese. No signup.