Going from Mandarin Chinese to Cantonese (粵語) has a composite linguistic distance of 22% (curated lexical data). Below is the dimension-by-dimension breakdown.
Shared vocabulary, cognates, and loanwords.
Morphology, syntax, word order, cases.
Shared sounds and phoneme inventory.
Chinese → Chinese
Sino-Tibetan ↔ Sino-Tibetan
The 5 languages with the lowest linguistic distance from Mandarin Chinese:
A quick 3-question check between Mandarin Chinese and Cantonese. No signup.