Slack Emoji Size Limit & Requirements
A Slack custom emoji must be 128KB or smaller and square, up to 128×128 px. Animated GIFs also need a short loop to keep animating after upload. Here are the exact limits and the fastest way to meet them.
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File size limit: 128KB
Slack rejects any custom emoji over 128KB. This is the hard cap most uploads fail on. A short, low-color GIF compresses under it reliably.
Dimensions: square, up to 128×128 px
Slack custom emoji must be square. Slack accepts up to 128×128 px and scales the display down. Non-square images are rejected, so crop to a square first.
Frames: keep the loop short
The hard limits are size and dimensions. Frame count is not an official cap, but a short loop (around 50 frames) helps fit 128KB and keeps animation after Slack re-encodes the file.
How it works
Know the two hard limits
128KB file size and 128×128 square dimensions. A GIF must meet both to upload; a short loop helps it stay animated.
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 custom emoji must be **128KB or smaller**. Files over 128KB are rejected at upload. The limit applies to both static and animated (GIF) emoji.
What dimensions should a Slack emoji be?
A Slack emoji must be **square**, up to **128×128 pixels**. Slack scales it down for display, but the uploaded file has to be square — non-square images are rejected.
How many frames can a Slack emoji GIF have?
Slack does not publish an official frame cap — the hard limits are 128KB and 128×128. In practice, keeping an animated emoji to **around 50 frames** helps it stay under 128KB and keep animating after Slack re-encodes it.
What file types does Slack accept for emoji?
Slack accepts **.gif, .png, .jpg, and .apng** for custom emoji. For animation, use a .gif that fits the 128KB and 128×128 square 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.