9BabyNames Baby names with meanings & US popularity data

Sibling Name Match Calculator

Enter any two baby names to see how well they work as a sibling pair. The tool scores 6 compatibility dimensions: alliteration, ending sound, length, letter overlap, cultural origin, and popularity-era overlap. Out of 100.

How the score works

The total compatibility score is summed from 6 weighted signals (max 100):

  • Same starting letter (18 pts) — classic alliteration sibling pattern
  • Same ending sound (15 pts) — phonetic-rhythm match
  • Length proximity (12 pts max, 8 if differ by 1, 4 if by 2)
  • Letter overlap (15 pts max, scaled by % shared unique letters)
  • Same cultural origin (20 pts) — Hebrew + Hebrew, Spanish + Spanish, etc.
  • Popularity-era overlap (20 pts max) — both in SSA top 200 the same years (1980+)

The signals are derived from sibling-name patterns we documented in the Sibling Name Patterns report. Three of these patterns (alliteration, shared origin, vowel-rhythm) appear consistently in 145 years of US co-occurrence data.

Note: Compatibility scoring is heuristic, not predictive. A "low score" doesn't mean two names don't go together — it means they don't follow common formal patterns. Plenty of well-matched sibling pairs (Henry & Charlotte, Julia & Marcus) score modestly here because their match is semantic / cultural rather than formal. Use this as one signal among many. Origin lookups use our editorial name dictionary; if a name isn't in our database the origin signal returns 0 even when both names share roots.

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