Going from Portuguese to Czech (ฤeลกtina) has a composite linguistic distance of 63% (heuristic estimate). Below is the dimension-by-dimension breakdown.
Shared vocabulary, cognates, and loanwords.
Morphology, syntax, word order, cases.
Shared sounds and phoneme inventory.
Latin โ Latin
Indo-European โ Indo-European
The 5 languages with the lowest linguistic distance from Portuguese:
A quick 3-question check between Portuguese and Czech. No signup.