Slack message character counter
Slack truncates messages that exceed 40,000 characters, encouraging long content to move into files, canvases, or threaded summaries. The limit counts spaces, line breaks, markdown-style formatting, mentions, emoji, links, and pasted logs. API clients may also warn or truncate text, so long incident updates should be measured before posting.
Slack message character limit
The 40,000-character limit prevents oversized Slack messages from degrading channel readability and client performance. Longer material belongs in linked docs or files.
Examples
Counts use plain character lengthIncident update: checkout errors are down after rolling back the payment worker. Next check at 14:30 UTC. Logs and dashboard links are in thread.
Incident update: checkout errors are down after rolling back the payment worker. Next check at 14:30 UTC. Logs, dashboard links, deploy history, customer reports, database checks, vendor messages, timeline notes, and action items are all included in this channel message.
Release notes for staging: new export menu, fixed smart quotes, and updated onboarding copy. Please test imports before EOD.
Release notes for staging: new export menu, fixed smart quotes, updated onboarding copy, revised permissions, faster imports, mobile toolbar fixes, analytics changes, migration notes, test accounts, screenshots, and rollout tasks. Please test imports before EOD.
Slack character limit FAQ
- How many characters are allowed in Slack?
- Slack has a 40,000-character limit.
- Why does Slack message have a character limit?
- The 40,000-character limit prevents oversized Slack messages from degrading channel readability and client performance. Longer material belongs in linked docs or files.
- Do spaces count toward the Slack limit?
- Yes, spaces count toward character limits on all major platforms.
- What happens if I exceed the Slack limit?
- The platform usually rejects the message or truncates it. Use the counter above to stay safely under 40,000 characters.