Slack Channel Name Rules: 45 Names Tested in the App and the API

A Slack channel name can be up to 80 characters long. It may contain lowercase letters, numbers, hyphens (-) and underscores (_), plus letters from other scripts such as Japanese, Korean or accented Latin. It may not contain capital letters, spaces, periods, other punctuation or emoji. On 7 October 2026 we tried 45 names in a free-plan test workspace, typing some into Slack's Create a channel dialog and sending the rest to the API with conversations.create and conversations.rename. The tables below are what Slack returned for each one.

The rules in one table

What the Create a channel dialog does as you type

The dialog fixes two things for you and flags the rest. We typed W7 Q3 Plan.Budget! and the box showed w7-q3-plan.budget! before we pressed anything else: capitals became lowercase and each space became a hyphen. The period and the exclamation mark stayed, and the red line under the box read "Channel names can't contain spaces or punctuation. Use dashes to separate words." The Next button stays grey until the name is valid.

The number at the right of the box counts down from 80. At 85 characters it read -5 in red with "Channel names can't be longer than 80 characters." An emoji counts as 2 in that counter: w7-launch-🎉 is 11 characters on screen and the counter showed 68, not 69. With the emoji in the name, the error was "For some weird reason, that didn't work. Please try again to continue.", which does not say the emoji is the problem. Delete the emoji and the error goes away.

A name already in use gets its own line: "That name is already taken by a channel, username, or user group in Slack."

Every name we sent to the API

These went to conversations.create with the signed-in user's session, one call per name. The API does not fix anything for you: a name the dialog would have lowercased comes back as an error.

The 80-character limit counts characters, not bytes: 80 Japanese characters passed even though they take 234 bytes in UTF-8. Capital letters are refused in every script we tried, including Ü.

Names that are taken without a channel you can see

Three results surprised us.

Accented names block their plain twin. Slack stores a name_normalized copy with the accents removed. After w7-ünïcode existed, creating w7-unicode returned name_taken, although no channel with that exact name was in the list.

Archived channels keep their names. We archived w7-archive-demo and then tried to create a new channel with that name: name_taken. To reuse the name, rename or delete the archived channel first. Our guide to archiving a Slack channel shows the archive and delete steps.

Deleted and renamed channels free their names at once. We deleted w7-한글 in the app and created w7-한글 again a minute later: ok. We renamed w7-rename-demo to w7-renamed, and creating a new w7-rename-demo straight after worked too.

here, everyone and channel are taken because Slack uses them as mentions (@here, @everyone, @channel). general was free in our workspace, because Slack named its default channel #all-slack when the workspace was made.

Private channels block public ones. We made a private channel w7-priv and then asked for a public w7-priv: name_taken. Members who cannot see the private channel get the same error and no hint why.

Changing a channel name

Renaming follows the same rules. conversations.rename returned invalid_name_specials for W7-Rename and for w7 renamed, name_taken for social, and invalid_name_maxlength for 81 characters. In the app, click the channel name, then Edit next to Channel name on the About tab.

Each rename posts a line in the channel ("has renamed the channel from ... to ..."), and conversations.info keeps the old names in previous_names. Renaming a channel to the name it already has returned ok, posted "has renamed the channel from "w7-renamed" to "w7-renamed"" and added a second w7-renamed to previous_names. A script that sets a name on a schedule should compare first.

The channel ID stayed the same after each rename, so anything that stores the ID keeps working. A bot that posts by channel name needs the new name; see Slack channel_not_found for that error.

FAQ

Can a Slack channel name have capital letters? No. The app lowercases them as you type, and the API refuses them with invalid_name_specials. The sidebar always shows the name in lowercase.

What do people use instead of spaces and periods? Hyphens, mostly: team-design, proj-q3-launch. Slack's own dialog suggests the prefixes help-, proj- and team- when the name box is empty.

Is there a minimum length? One character is enough: the name x was accepted. Only an empty name failed, with invalid_name_required.

Can the general channel be archived to free its name? No. Archiving the workspace's general channel (here #all-slack) returned cant_archive_general.