Going from Hebrew to Yiddish (ייִדיש) has a composite linguistic distance of 64% (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.
Hebrew → Hebrew
Afro-Asiatic ↔ Indo-European
The 5 languages with the lowest linguistic distance from Hebrew:
A quick 3-question check between Hebrew and Yiddish. No signup.