Resize any image for a Slack emoji

How to resize an image for Slack

Slack asks for a square image of 128 × 128 pixels under 128 KB. Most pictures are neither square nor that small, so there are two jobs: choose the area you want, then shrink it without making it blurry or too heavy.

This tool does both. You move and resize a square over your picture, then it crops the selected area and resizes it in several gentle steps, which avoids the jagged edges a single big downscale gives.

Tips for emojis that stay readable at small size

An emoji is shown at around the size of a line of text, so details disappear fast.

• Crop tight: fill the square with the subject (a face, a logo mark) instead of the whole scene.
• Prefer simple shapes and strong contrast; thin lines and small text blur away.
• Use a transparent background when you can; see transparent Slack emojis.
• Check the preview on light and dark backgrounds before downloading, as Slack themes differ.

Supported files and privacy

You can drop PNG, JPEG, WebP, AVIF, BMP or GIF files up to 10 MB. SVG, HEIC and TIFF are not supported yet; export them to PNG or JPEG first.

The resize runs entirely on your device, so your picture is never sent to a server. Read the privacy details for how that works.

Frequently asked questions

Will resizing make my image blurry?

Going down to 128 × 128 always loses detail, but the tool downsizes in steps for a cleaner result. Cropping tightly on the subject helps the most.

Can I resize a photo from my phone?

Yes. Open the page in your phone browser and pick the photo. If it is HEIC, convert or share it as JPEG first, since HEIC is not supported yet.