Choose an X username that is short, sayable out loud, and the same name you use everywhere else, inside the rules X actually enforces: a new handle is 4 to 15 characters, and it can contain letters, numbers and underscores only. Get those two things right and the rest is preference.
The part most people get wrong is assuming they can find out what is free before they go looking. They cannot, and neither can any tool. Below: the rules, what separates a good handle from a burner-looking one, and what it costs to change later.
The rules X enforces
4 to 15 characters for a new handle. The maximum applies to everybody. The minimum applies only to handles registered now, which is the detail that confuses people: accounts created before that rule still hold one, two and three character handles and are allowed to keep them. You will see them, and you cannot register one.
Letters, numbers and underscores only. No dots, no dashes, no spaces, no accented characters and no emoji. This is the rule that quietly kills good ideas: a name with a hyphen or an accent does not survive the trip, so decide how you are spelling it without them rather than finding out at signup.
Handles are case-insensitive. @AnaRuiz and @anaruiz are the same account. Capitalisation is a display choice, useful for readability in a two-word handle, and never a way to claim one somebody already has.
"twitter" and "admin" are reserved. Handles containing either substring are blocked at signup, with an exception for verified accounts. X does not document this on a developer surface, so treat it as a rule to design around rather than argue with: if your brand name contains either word, plan for rejection.
What makes a handle actually work
Within the rules, four things separate a handle you will still like in three years from one you will quietly want to change.
Short. Your handle appears in every reply, every quote and every time somebody recommends you to a friend, competing for space with the message itself. Fifteen characters is the ceiling, not the target.
Sayable out loud. Apply the podcast test: can somebody say your handle on a call and have the listener type it correctly first time? Underscores fail badly, because "underscore" has to be pronounced and then counted. Numbers standing in for letters fail too. If you have to spell it out character by character, it is not working.
Not a near-miss of a bigger account. A handle one character away from a large account in your field buys you a permanent trickle of misdirected mentions and a permanent risk of looking like an impersonation attempt. It feels like borrowed relevance. It is a tax you pay forever.
The same name you use elsewhere. One handle across platforms means people can find you by guessing, which is how most people look for an account, and anything printed or spoken works everywhere. Where the exact match is gone on one platform, a consistent variant everywhere beats a perfect name on one and a random one on the rest.
When the one you want is taken
It will be. Every common first name, every one-word noun and almost every short brand name went years ago. The question is what you reach for next, and there is a clear ranking.
A second word is the best answer. If @anaruiz is gone, @anaruizbooks or @bookshopana beat anything else on this list. A second real word is sayable, memorable, searchable, and it tells a reader something before they click. Pick one that will stay true: a niche, a craft or a category, rather than a job title you might leave.
A number is the worst answer. A trailing number reads as a burner account or a bot to a large share of the platform, which is not fair but is real. A birth year dates you and a random digit says nothing. A number that means something publicly, a city code or a founding year that is part of the brand, is tolerable; a random one is not.
An underscore run is worse than it looks. @ana__ruiz is legal, unsayable and impossible to recall correctly. One underscore between two words is fine. Two or more, or a leading or trailing one, is the clearest signal of a handle chosen in a hurry after three rejections.
One option people forget: shorten rather than extend. A shorter handle that drops your first name usually beats a longer one that keeps it.
Nobody can tell you what is available except X
This is the part every other page on the topic dodges. There is no public list of free X handles and no API that answers "is this available". Any site showing a green tick next to a handle is either probing X for each name you type, or guessing.
Probing is unreliable for reasons that have nothing to do with the tool's quality. A handle can be held by a suspended account, which looks free and is not. It can be reserved by X, blocked for containing a restricted word, or taken between the moment you check and the moment you sign up. A third-party availability answer is a snapshot of something that was never authoritative.
That is why the username generator validates format rather than availability, and says so. A suggestion that passes the length rule, the character rule and the reserved-word rule is a suggestion you can actually attempt. A green tick from a third party is a suggestion you have to attempt anyway.
Changing your handle, and what it releases
You can change your X username whenever you like, from account settings. Your followers, posts and history all come with you. That part is easy, which is why the consequence catches people out.
Your old handle is released immediately, to anyone. There is no grace period and no reservation. The second you confirm the change, the old name is available for registration by a stranger, and people do watch for exactly this.
With one exception worth knowing before you plan around it: a handle obtained through X's paid handle marketplace goes back to X rather than into general circulation. If that is how you got the one you are leaving, you cannot grab it on a second account afterwards, because it was never yours to release.
The damage that follows is all pointing damage. Every link to your old profile URL stops resolving to you, and every @mention of the old handle in old posts, including posts by people recommending you, now points at whoever registers it next. QR codes on printed material, the link in your email signature, the profile link on your website: all of it now leads somewhere you do not control.
So the sequence matters. If anything real points at the old handle, register the old name on a secondary account the moment it frees up, and park it with a post saying where you went. If nothing points at it, which is true for most small accounts, change it freely and stop worrying. The cost of a handle change scales with how long you have had it, which is the argument for spending twenty minutes on the decision now.
Your display name is separate, and free to change
The bold line at the top of your profile is a different field with different rules. It holds 50 characters, it accepts spaces, punctuation, accents and emoji, and you can change it as often as you like with no consequences at all: nothing is released, no link breaks, nobody has to be told.
That is where your keywords belong. A handle is a name, and stuffing it with a keyword produces something long, unsayable and permanent. The display name can carry the role or the niche ("Ana Ruiz, bookshop ecommerce") and be edited the week your focus changes. Between it and the 160 characters underneath, the profile has room for keywords without touching the handle. What goes in those 160 is covered in what to put in your X bio.
One caution: the bold and script letters you see in some display names are substituted Unicode characters rather than formatting, and the trade-offs are covered in the bold text guide. For a field that search matches and screen readers announce, it is the wrong place to spend the novelty.
Frequently asked questions
Can you change your X username?
Yes, from your account settings, and as often as you like. The catch is that your old handle is released immediately and anybody can register it, so every link, QR code and old mention pointing at it now leads somewhere you do not control. If the old handle has anything pointing at it, claim it on a second account the moment it frees up.
How many characters can a Twitter username be?
A new X (Twitter) username is 4 to 15 characters. The 15-character maximum applies to everyone. The 4-character minimum applies only to handles registered now: accounts created before that rule still hold one, two and three character handles, which is why you will see them on the platform and cannot register one yourself.
What characters are allowed in an X username?
Letters, numbers and underscores only. No dots, no dashes, no spaces, no accented characters and no emoji. Handles are also case-insensitive, so @AnaRuiz and @anaruiz are the same account and capitalisation is a display choice rather than a way to claim one that is taken.
Can I check if a Twitter username is available?
Only on X itself. No third party has a reliable availability list: any tool that claims to know is probing X, and its answer can be stale or wrong, because a handle can be held by a suspended account, reserved by X or blocked. Get the format right first, then check the shortlist on X.
What happens to my old handle when I change it?
It becomes available to anyone straight away. Links to the old profile URL stop resolving to you, and @mentions of it in old posts now point at whoever registers it next. If you have printed material, a website link or any real audience pointing at the old handle, register it on a secondary account immediately after the switch.
Should my X handle match my name on other platforms?
Yes, wherever possible. One handle across platforms means people can find you by guessing and anything printed or spoken works everywhere. If the exact match is gone on one platform, a consistent variant everywhere beats a perfect name on one and a random one elsewhere.
With the handle settled, what decides whether a visitor stays is the bio and the first post they see: what to put in your X bio and what to post when you have run out of ideas. The rest of the section is at the X guides hub.