What actually makes a username rare
Usernames are first come, first served, so scarcity comes down to arithmetic. There are 26 one-letter names, 676 two-letter names and 17,576 three-letter names on a platform that allows letters only. Hundreds of millions of people have signed up to the big apps, so every short combination and every common word was claimed years ago. This username rarity checker scores a handle on exactly those factors.
Length matters most. Each extra character multiplies the number of possible names by 26 or more, which is why a four-letter name is dozens of times easier to find free than a three-letter one. Real words score highest of all, because each word exists only once per platform and people search for them.
Characters matter next. Numbers on the end (alex99), underscores and periods are the classic workarounds when a name is taken, so names using them are plentiful and score lower. A short invented word that's easy to say, like nova or kiro, sits in the sweet spot: rare enough to feel premium, but still findable.
Remember that rarity and availability are different questions. The score tells you how scarce a name's shape is; only a live check tells you whether this exact name is free on Instagram, TikTok, YouTube and the rest. Press Check availability to run it across 25 platforms and the matching domains.