Creating a custom emoji takes two minutes and requires workspace admin access

A Slack emoji is a small image or icon that you upload to your workspace so team members can use it in messages, reactions, and threads — just like the built-in smiley faces and thumbs-up that come with Slack. You create them from your workspace settings, and once uploaded, they appear in the emoji picker alongside everything else. Only workspace admins and owners can add new emojis, but anyone in the workspace can use them once they exist.

The process is straightforward: you pick an image file, upload it through Slack's emoji settings, give it a name, and it's live. The image should be square, at least 128 pixels wide, and under 128 kilobytes. Most people use PNG or JPG files, though Slack also accepts GIF for animated emojis.

Key Takeaways

  • Only workspace admins and owners can upload custom emojis, though anyone can use them once they exist.
  • Your image file should be square, at least 128 pixels wide, and smaller than 128 kilobytes in size.
  • You upload emojis through Workspace Settings > Emoji Management, not through your personal settings.
  • The emoji name you choose is what people type to find and use it — use something memorable and related to the image.

Where to find the emoji upload tool

Go to your workspace name in the top left corner of Slack and click it. A menu appears. Select "Settings and administration" and then "Workspace settings." You'll see a sidebar on the left; click "Emoji Management" near the bottom.

If you don't see "Emoji Management," your workspace may have restricted emoji uploads to owners only. Ask your workspace owner to check the permissions, or ask them to upload the emoji for you. Some organizations disable custom emojis entirely, in which case this option won't appear at all.

Preparing your image file

The image needs to be square — the same width and height. If you have a rectangular image, crop it to a square first. Use any image editor: Photoshop, GIMP (free), Preview on Mac, or even online tools like Pixlr or Canva.

Make sure the file is at least 128 pixels by 128 pixels. Slack will accept smaller images, but they'll look blurry when people use them. Aim for 256 by 256 pixels or larger if you can. The file size must be under 128 kilobytes — most PNG and JPG files are well under this limit, but if you're uploading a high-resolution image, you may need to compress it. Online tools like TinyPNG will shrink the file without losing much quality.

Uploading and naming your emoji

In Emoji Management, click "Upload Custom Emoji" or the upload button (usually a plus sign or upload icon). Choose your image file from your computer. Slack will show you a preview of how it will look.

Type a name for the emoji in the text field. This is the name people will type to use it — for example, if you name it "party_parrot," someone would type :party_parrot: to insert it. Use lowercase letters, numbers, and underscores only. Avoid spaces and special characters. Make the name short and descriptive so people can remember it and find it easily in the emoji picker.

Click "Save" or "Upload." The emoji is now live in your workspace. It will appear in the emoji picker under "Custom" and in search results when people type the name.

Using aliases to make emojis easier to find

After you upload an emoji, Slack lets you add aliases — alternate names that do the same thing. If you upload an emoji named "thumbs_up_custom" but people are used to typing :thumbsup:, you can add that as an alias so both names work.

Go back to Emoji Management, find your emoji in the list, and click it. You'll see an "Add Alias" option. Type the alternate name and save. Now people can type either name and get the same emoji. This is useful if your emoji has a common nickname or if you want to replace a built-in emoji with a custom version.

Animated emojis with GIF files

If you upload a GIF file instead of a static image, the emoji will animate when people use it. The same size and file-size rules explore — square, at least 128 pixels, under 128 kilobytes. GIFs loop automatically, so make sure the animation looks good when it repeats.

You can create a GIF in Photoshop, GIMP, or free online tools like ezgif.com. Keep the animation short — two to three seconds is typical — so it doesn't distract in busy channels. Animated emojis are fun for celebrations, reactions, or branded team moments, but they can slow down Slack on older devices if too many are used at once.

Troubleshooting common upload problems

If Slack rejects your image, the most common reasons are file size (over 128 KB), wrong dimensions (not square), or an unsupported format. Check that your file is PNG, JPG, or GIF. If the file is too large, use an online compressor or resize it in an image editor.

If the emoji name is rejected, you probably used a space or special character. Slack only accepts letters, numbers, and underscores. If you see "You don't have permission to add emoji," you're not an admin or owner. Ask your workspace owner to upload it, or ask them to give you emoji management permissions.

Frequently Asked Questions

Can I delete or edit an emoji after I upload it?

Yes. Go to Emoji Management, find the emoji in the list, and click it. You'll see options to edit the name, add aliases, or delete it entirely. Deleting an emoji removes it from the picker, but messages that already used it will show a broken image or the emoji name in text.

What happens if I upload an emoji with the same name as a built-in one?

Slack won't let you. If you try to name your custom emoji "smile" or "thumbsup," it will tell you the name is taken. You can add an alias to a built-in emoji, but you can't replace it with a custom image.

Can people outside my workspace use my custom emojis?

No. Custom emojis only work within the workspace where you uploaded them. If someone from another workspace visits yours as a guest, they can see and use your custom emojis, but they can't take them to their own workspace.

Is there a limit to how many custom emojis I can upload?

Slack's free plan allows unlimited custom emojis. Paid plans also have no hard limit, though very large emoji libraries may slow down the picker slightly. Most workspaces have hundreds without any issues.

Can I bulk upload multiple emojis at once?

Not through the standard Slack interface — you upload them one at a time. However, Slack's API allows developers to automate bulk uploads if your workspace uses a custom integration or bot. For most teams, uploading a few emojis manually is faster than setting up automation.