Slack Emoji Size & Format Guide
Slack says square images under 128 KB with transparent backgrounds work best. JPG, PNG, and GIF are supported, and animated GIFs can contain up to 50 frames. A 128x128 export is a practical target for predictable, crisp rendering.
Quick answer
Slack sizes at a glance
Use a square JPG, PNG, or GIF under 128KB. Export at 128x128px for a reliable small-screen result; use PNG for transparency or GIF for animation, with no more than 50 frames.
Pick this preset, drop your file, and FastEdit starts from the Slack Custom Emoji dimensions, format, and file-size target.
Slack Image Size Cheat Sheet
Custom Emoji
128x128 PNG / GIF Max 128 KB
Practical custom emoji target. Slack says square images under 128KB work best; PNG supports transparency and GIF supports animation.
Open Slack Custom Emoji preset →Profile Photo
512x512 PNG / JPEG Max 1 MB
Workspace profile picture. Displayed at various sizes in messages, sidebars, and profiles. Square crop recommended.
Open Slack Profile Photo preset →Before you upload
- Use PNG with transparency for emoji that need to blend into Slack's message background.
- Keep emoji designs simple with bold shapes: they render as small as 22px in message text.
- Animated GIF emoji are supported but tend to be distracting in busy channels: use sparingly.
- Slack displays profile photos as small as 24px in compact view, so avoid fine detail and small text.