Slack Emoji Size Limit & Requirements
Slack says square images under 128KB and with transparent backgrounds work best for custom emoji. JPG, PNG, and GIF are supported, and animated GIFs can include up to 50 frames. Here is the official guidance and a practical way to prepare the file.
Files stay in your browser. No upload. No watermark.
Make a Slack-ready EmojiDrop a GIF here
or
Recommended file size: under 128KB
Slack says custom emoji under 128KB work best. A short, low-color GIF reaches that target more reliably than a long or detailed animation.
Shape: square works best
Slack recommends a square image but does not publish a pixel maximum. This tool uses a 128×128 px square output as a practical standard for emoji display.
Frames: up to 50 for animated GIFs
Slack allows animated GIF emoji to include up to 50 frames. A shorter loop also helps the file fit 128KB and keep animating after Slack re-encodes it.
How it works
Know the Slack rules
Slack recommends a square image under 128KB. Animated GIFs can include up to 50 frames, and shorter loops are easier to read at emoji size.
Crop, scale, and compress to fit
Use the Slack preset to center-crop to square, scale to 128px, and target 128KB in one step — locally in your browser.
Upload and verify
Download the .gif and add it in Slack as a custom emoji. If it still fails, the file is usually over 128KB or not square.
FAQ
What is the Slack emoji size limit?
Slack says square custom emoji **under 128KB work best**. The help page presents this as guidance rather than an official rejection threshold. This tool targets under 128KB for reliable results.
What dimensions should a Slack emoji be?
Slack recommends a **square** image but does not list a pixel maximum. **128×128 px** is a practical standard size, so this tool uses it as the default output.
How many frames can a Slack emoji GIF have?
A Slack animated GIF emoji can include **up to 50 frames** — this is stated in Slack's own help docs. Staying at or under 50 frames also helps the file fit 128KB and keep animating after Slack re-encodes it.
What file types does Slack accept for emoji?
Slack accepts **JPG, PNG, and GIF** for custom emoji. For animation, use a GIF that fits the 128KB, square, and 50-frame limits.
How do I make a GIF fit the Slack emoji limits?
Use the [GIF compressor for Slack](/slack-emoji-gif) on this site — it crops to square, scales to 128px, and compresses under 128KB locally. See the [step-by-step guide](/how-to-make-slack-emoji-gif) for the full process.
Does this upload my GIF?
No. The compression flow is designed to run locally in your browser.