Slack channel names can be at most 80 characters and may only contain lowercase letters, numbers, hyphens and underscores, according to Slack's developer docs. The name is checked every time a channel is created, and a name that's already in use comes back with a name_taken error, so you'll need another one.
Eighty characters sounds generous, and for a single channel that's true. The limit starts to matter when you build a naming system for clients, projects and teams, or when a script creates channels automatically and needs to know exactly what will be rejected.
The naming rules at a glance
| Item | Limit | Applies to |
|---|---|---|
| Channel name length | 80 characters or less | Public and private channels created via conversations.create |
| Allowed characters | Lowercase letters, numbers, hyphens, underscores | Channel names |
| Duplicate name | Rejected with name_taken | New channels |
| Over-length name | Rejected with invalid_name_maxlength | New channels |
| Punctuation-only name | Rejected with invalid_name_punctuation | New channels |
| API rate for new channels | Tier 2, 20+ per minute | conversations.create |
These come from the API reference for the conversations.create method, which validates the name every time a channel is created, public or private.
No capitals, no spaces
The rule that shapes everything is the character set. The Slack developer docs list lowercase letters, numbers, hyphens and underscores as the allowed characters, and nothing else. So a name like Client Onboarding Q1 won't pass as written. It has to become something like client-onboarding-q1.
That's why most workspaces settle on hyphens as word separators. Underscores work too, but mixing the two makes channels harder to find, because people type one and the channel uses the other. Pick one and stick to it.
Errors you'll run into
- name_taken: a channel with that name already exists. Choose a different name.
- invalid_name_maxlength: the name is over 80 characters.
- invalid_name_punctuation: the name is only punctuation.
- invalid_name_required: the name is empty.
- invalid_name_specials: the name contains characters outside the allowed set.
- invalid_name: a general invalid name.
- restricted_action: a workspace preference stops this user from creating channels at all.
The last one isn't about the name. If someone on your team can't create a channel however they spell it, it's a workspace setting, and an admin needs to look at who's allowed to create channels.
If you create channels with a script
For anyone automating channel creation, say a new channel per client or per project, a few details from the API reference matter. The same method creates public or private channels; set is_private to true for a private one. It's a Tier 2 method, which allows 20+ requests per minute per method, per workspace, per app, so a bulk setup of a hundred channels needs pacing.
Store both the channel's id and its name from the response, as Slack recommends. Names can change later; the id doesn't, so anything that posts to the channel should use the id.
Before your script sends a name, normalise it: lowercase everything, swap spaces for hyphens, strip anything outside the allowed set, and cut it to 80 characters. That avoids most of the errors above before they happen.
A naming pattern that stays under the limit
A short prefix system keeps names readable and sorted. Something like client-acme-website or proj-spring-launch or team-sales tells people what a channel is for at a glance, and channels with the same prefix sit together in the sidebar. Keep the descriptive part short; a channel name you can read without scrolling is far more useful than one that uses all 80 characters.
The same thinking works anywhere you name things at scale. This UTM naming template uses a similar prefix pattern for campaign tags. When a project ends, archiving the Slack channel keeps the sidebar clean without losing the history, and frees you from inventing new names that dodge old ones.
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How Teams handles channel names
Microsoft Teams works differently. Its channel names can't contain characters such as ~ # % & * { } + / \ : < > ? | ' " or the word forms, and can't start with an underscore or period or end with a period. Those are blocked characters rather than a length rule, so the two systems don't translate one to one. If you're comparing chat tools more widely, here's my list of team chat apps to compare.
My advice for naming channels
Write your naming convention down before the workspace grows: lowercase, hyphens between words, a short prefix for the type of channel, and a name someone can guess without searching. If you automate channel creation, normalise every name in code and store the id. You'll rarely get near 80 characters, and nobody will be hunting for a channel spelled three different ways.
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Frequently asked questions
How long can a Slack channel name be?
80 characters or less, per Slack's developer docs.
Can a Slack channel name have spaces or capitals?
The documented characters are lowercase letters, numbers, hyphens and underscores only.
What if the name is taken?
The API returns name_taken, so pick a different name.
Can I change a channel name later?
Yes. That's why it's worth storing the channel id, which stays the same when the name changes.
Does Teams use the same rules?
No. Teams lists a different set of blocked characters and words.
