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ImgWrench

Slack Emoji Resizer

Specs checked against Slack Help · 2026-10-24
Slack emoji
128* px
Formats
PNG, GIF
Full specs ↓
Export:

Processed in your browser — nothing is uploaded. Fit, sharpening and the chat preview appear after you add an image.

Size and format specs

OutputSizes (px)FormatsMax file sizeTransparency
Slack emoji128×128*PNG, GIFPNG 128 KB, GIF 128 KBYes
Discord emojiBonus export128×128PNG, GIFPNG 256 KB, GIF 256 KBYes
Twitch emoteBonus export112×112, 56×56, 28×28PNG, GIFPNG 100 KB, GIF 512 KBYes

* Our pick: no exact size is published for this, so we export one that stays sharp.

Specs last verified: 2026-10-24

ImgWrench's Slack emoji resizer turns any image or animated GIF into a square custom emoji that follows Slack's own advice: square, under 128KB, transparent where possible, and no more than 50 frames for GIFs.

How to make a Slack emoji

  1. Drop your image or GIF into the tool above.
  2. If it isn't square, choose Contain, Cover or Crop.
  3. Check the size badge: anything over 128KB is shrunk for you.
  4. Download the emoji and add it to your workspace from Slack's custom emoji menu.

What Slack asks for

Slack's help page, "Add custom emoji and aliases to your workspace", says images can be JPG, PNG or GIF, that square images under 128KB with transparent backgrounds work best, and that GIFs can include up to 50 frames. It doesn't give a pixel size, so the 128×128 size here is ImgWrench's choice.

Design tips

  • Transparent background. A PNG or GIF with a clear background sits cleanly on light and dark themes.
  • Bold and simple. Emoji are shown small in messages; thick shapes read better than fine detail.
  • Short loops. Fewer frames keep animated emoji under 128KB without losing colour.

Frequently asked questions

How do I resize an image into a Slack emoji?

Drop your image or animated GIF into the tool above; you can add several at once. If it isn't square, choose Contain, Cover or Crop. Each emoji comes out as a 128×128 PNG or GIF and is shrunk to fit under 128KB if it needs to be. Download it, then add it to your workspace from Slack's custom emoji menu.

What size should a Slack emoji be?

Slack doesn't give a pixel size. Its help page says square images under 128KB, with transparent backgrounds, work best, in JPG, PNG or GIF. ImgWrench exports 128×128, a size we chose: it's square, sharp at the small size emoji are shown at, and keeps files comfortably under 128KB.

Can I make an animated Slack emoji?

Yes. Drop in an animated GIF and every frame is resized and kept in time. Slack allows up to 50 frames, so longer GIFs have frames dropped evenly to fit, without changing how long the loop lasts, and colours are reduced if the file is still over 128KB. The file shows its frame count and size before you download.

My Slack emoji GIF is too big. What can I do?

The resizer already shrinks GIFs towards 128KB by using fewer colours and frames. For more control, open the GIF in the GIF editor: crop it to the part that matters, slow it down or keep every 2nd frame, then bring the result back here. Shorter, simpler loops make the smallest emoji.

Can I use the same emoji on Discord or Twitch?

Yes. Tick Discord emoji or Twitch emote and ImgWrench also exports Discord's 128×128 emoji and Twitch's 112, 56 and 28px sizes from the same upload, each checked against that platform's own limits. For a full Discord set with a chat preview, use the Discord emoji resizer.

Are my images uploaded anywhere?

No. Everything happens in your browser: ImgWrench resizes your images on your own device, and they are never sent to a server or stored anywhere else. You can confirm this yourself by opening your browser's network tab while you use the tool and checking that no request carries your image data.