Slack Emoji & Image Sizes
Slack custom emoji should be square, ideally 128x128 pixels, in PNG or GIF format, under 128 KB. While Slack will resize larger images, uploading at the target dimensions ensures crisp rendering across desktop and mobile. FastEdit makes it easy to crop, resize, and optimize images for Slack in one click.
Pick this preset, drop your file, and FastEdit starts from the Slack Custom Emoji dimensions, format, and file-size target.
Slack Image Size Cheat Sheet
Custom Emoji
128x128 PNG / GIF Max 128 KB
Workspace custom emoji. Square aspect ratio required. Transparent backgrounds are supported with PNG format. GIF emoji can be animated.
Open Slack Custom Emoji preset →Profile Photo
512x512 PNG / JPEG Max 1 MB
Workspace profile picture. Displayed at various sizes in messages, sidebars, and profiles. Square crop recommended.
Open Slack Profile Photo preset →Before you upload
- Use PNG with transparency for emoji that need to blend into Slack's message background.
- Keep emoji designs simple with bold shapes: they render as small as 22px in message text.
- Animated GIF emoji are supported but tend to be distracting in busy channels: use sparingly.
- Slack displays profile photos as small as 24px in compact view, so avoid fine detail and small text.