Slack GIF Limits and Best Practices

Slack GIF size limits

What happens if your GIF exceeds 1 MB?

GIFs over 1 MB are uploaded as file attachments instead of displaying inline. Team members see a file icon with a download button — the animation doesn't play automatically in the chat. This significantly reduces engagement.

How to compress a GIF for Slack

1. Go to gifmash.com/compress-gif-for/slack
2. Upload your GIF — the compressor is pre-configured for 1 MB / 400 px wide
3. Use Target Size mode with 950 KB (a safe margin below 1 MB)
4. Download and share in Slack — it will display inline

Tips for Slack GIFs

• Keep it under 3 seconds — long GIFs get less engagement in fast-paced chat
• 400 px wide is enough — Slack's message area doesn't need larger
• 64–128 colors is usually fine for reactions and memes
• Use GIPHY integration for browsing — Slack's built-in GIPHY access already serves compressed GIFs

Slack custom emoji GIFs

Custom emoji in Slack must be under 128 KB (not 1 MB) and ideally 128 × 128 px. Animated emoji GIFs are supported but need aggressive compression to hit the 128 KB limit. Use GifMash's Target Size mode set to 120 KB and resize to 128 px wide.

Slack vs Discord: key differences

Discord's free inline limit is 8 MB — 8× higher than Slack's 1 MB. If you share on both platforms, compress for Slack's limit and the file will work everywhere.