Slack file size limits
Slack accepts big files, but custom emoji are tiny: square and under 128 KB works best. Okaysize makes emoji that fit.
Tools for Slack
Guides
Every Slack limit
| What | Official limit | Source |
|---|---|---|
| File upload | Up to 1 GB | slack.com |
| Custom emoji | Square, under 128 KB works best; GIFs up to 50 frames | slack.com |
Limits verified Oct 2, 2026 against official sources.
Report an outdated limitNot officially published: Emoji pixel size. We don't guess these.