Slack emoji size — the complete spec
Upload Slack custom emoji at 128×128 pixels, max 128 KB, as PNG, JPG or GIF. The 128 KB ceiling is the one that catches people out — it is half of Discord’s.
| What | Size | Max file | Format |
|---|---|---|---|
| Custom emoji (upload) | 128 × 128 px | ≤ 128 KB | PNG · JPG · GIF |
| Emoji in message (display) | 22 × 22 px | — | rendered size |
| Emoji in reaction (display) | 16 × 16 px | — | rendered size |
| Workspace icon | 512 × 512 px | ≤ 1 MB | PNG · JPG · GIF |
| Profile photo | 512 × 512 px | ≤ 1 MB | PNG · JPG · GIF |
Need one at exactly that size? The Pixel Forge is a free pixel maker that exports transparent GIFs at the size Slack wants — draw it, animate it, download it. Or grab the original dancing banana, pre-cropped for every platform.
Make a free Slack emoji →Want it as a real one? Dress your own dancing banana and get it printed as a vinyl sticker, mug or tee.
The gotchas nobody tells you
128 KB is the real limit, not the pixels
Most failed Slack uploads are file size, not dimensions. An animated GIF at 128×128 blows past 128 KB fast — cut frames, cut colours, or both. Pixel art wins here because it compresses to almost nothing.
It renders at 22 pixels — twenty-two
Slack shows emoji smaller than any other platform, and smaller again in reactions. Fine lines and detailed faces turn to soup. Silhouette first, detail never.
Animated emoji do work
GIFs animate in Slack messages and reactions. Keep them short and looping — a long animation reads as a distraction in a work channel, and eats the file budget.
You cannot resize after upload
Slack keeps what you gave it. Get the size right first, or you are deleting and re-uploading — and any message already using it loses the emoji.
Quick answers
What size should a Slack emoji be?
Upload at 128×128 pixels, maximum 128KB, in PNG, JPG or GIF format.
Can Slack emoji be animated?
Yes — upload an animated GIF. It animates in both messages and reactions, but must stay under the 128KB limit.
Why was my Slack emoji rejected?
Almost always file size. The limit is 128KB, much tighter than Discord’s 256KB — reduce frames or colours rather than dimensions.
More sizes: Telegram sticker size Discord sticker size Discord emoji size Twitch emote size · the full cheat sheet