Roblox username rules: length, characters and filters

Roblox accepts a username only if it passes a few format rules and its text filter. Knowing them saves you from failed sign-ups and wasted Robux on a name change that cannot go through.

The rules in short

On top of the format, every username passes the Roblox text filter, and it must not belong to another account, now or in the past.

Allowed characters

• Letters: English letters a to z. You can type capitals, and they will show in your name, but they do not create a different username: Nova, NOVA and nova are one name.
• Digits: 0 to 9, anywhere in the name.
• Underscore: _, at most once.

Everything else is rejected: spaces, hyphens, periods, letters with accents (é, ñ, ü), Cyrillic or other alphabets, and emoji. If you want those, use your display name instead, which is far less strict. See display name vs username.

The underscore rule

The underscore is the only symbol Roblox allows, with two limits:

• only one per username, so ki_ro_x is rejected;
• not at the start or the end, so _kiro and kiro_ are rejected.

The underscore is still useful. It turns a taken word into a free name: if Pixel is taken, Pix_el may not be.

The text filter

Roblox filters all text on the platform, usernames included, to block inappropriate content under its Community Standards. The filter itself is not public, but players regularly see it block:

• personal information, like something that looks like a phone number, an address or a full real name;
• words and parts of words the filter considers inappropriate, even if the whole name is innocent;
• names that pretend to be Roblox or its staff.

When a name fails the filter, Roblox tells you it is not appropriate, without saying which part triggered it. Try another spelling or move the underscore.

Names that fit but are not available

A name can pass every rule above and still be unavailable:

• Someone uses it now. Usernames are unique.
• Someone used it before. Past usernames stay tied to their account and nobody else can take them.
• It was retired. When a user uses their right to be forgotten, their past usernames are retired permanently.

Roblox shows whether a name is available when you sign up or change your username, before you pay.

Examples

• Novaletters only
• Nova_7one underscore inside
• K1roletters and a digit
• Zytoo short, 2 characters
• _Novaunderscore at the start
• No_va_7two underscores
• Nova Stara space
• Noéan accent

You can test any name against these rules on our Roblox page. The check runs in your browser and sends nothing anywhere.

What the error messages mean

When Roblox rejects a name at sign-up or in the change window, the message points to one of the rules above:

Rules for display names are different

Display names are free to change and do not have to be unique, so many of these rules do not apply in the same way. If all you want is a name that looks a certain way in games, read display name vs username first.

Tips for a good short name

• Aim for 4 or 5 characters. 3 character names are practically all taken; 5 letter readable names are the sweet spot. Read why in rare Roblox usernames.
• Use the underscore in the middle. Kai_x or Lu_na keep a name short and readable.
• Add one digit, not five. Wolf7 reads better than Wolf20481.
• Think in patterns. Consonant, vowel, consonant, vowel gives names like Rimo or Tavu that sound like words.
• Check before you pay. A username change costs 1,000 Robux, so test the format first, then see whether Roblox accepts it in the change window. Our guide on changing your Roblox username has the steps.

Read next: how to find available Roblox usernames.