Slack Custom Emoji Resizer128 × 128 px
Resize any image to exactly 128×128px for Slack. Free, instant, and nothing leaves your browser.
- Dimensions
- 128 × 128 px
- Aspect ratio
- 1:1
- Max file size
- 128KB
- Best format
- PNG
How to resize an image for Slack
Add your image
Click Choose image or drop a file into the box above. JPG, PNG and WebP all work.
Check the crop
The preset is already set to 128×128px. Drag inside the preview if you want to reposition the crop.
Download
Pick a format and click Download. You get a Slack Custom Emoji at exactly 128×128px.
Slack Custom Emoji size at a glance
Slack custom emoji at 128×128 are displayed at around 22px in messages. They're an important part of workspace culture and communication shorthand.
Why 128×128 matters
Custom emoji streamline communication and build team culture. Well-designed emoji get used constantly in reactions and messages.
What happens when the size is wrong
Detailed designs become unreadable blobs in chat. Files over 128KB get rejected. Poor transparency creates ugly boxes around emoji.
Best practices
- Design for 22px readability — that's the actual message display size.
- Use transparent backgrounds for seamless integration.
- Simple, high-contrast designs with bold lines work best.
Frequently asked questions
What size should a Slack Custom Emoji be?
The recommended size for a Slack Custom Emoji is 128×128 pixels (1:1 aspect ratio). The maximum file size is 128KB.
How do I resize an image for Slack Custom Emoji?
Upload your image to the resizer above. It will automatically crop and resize to 128×128px. Adjust the crop position if needed, then download the result. Your image never leaves your device.
Which format should I use for a Slack Custom Emoji?
Slack accepts JPG, PNG, GIF. We recommend PNG — Custom emoji for workspace reactions and messages. Displayed at small sizes in chat. Maximum 128KB.
Is my image uploaded anywhere?
No. TinyResize runs entirely in your browser. The file is read from your device, resized on your device, and downloaded from your device. Nothing is sent to a server.