Slack is used daily by millions of teams, but its image size requirements are scattered across help pages and often hard to find. Whether you're setting up a workspace for the first time or refreshing your profile, using the correct dimensions prevents blurry icons, unexpected crops, and compression artifacts. This guide covers every Slack image type with exact sizes and practical tips for 2026.

Slack Image Sizes — Quick Reference

Profile photo: 512×512 px recommended — PNG or JPG, max 1 MB, displayed as a circle
Workspace icon: 512×512 px — PNG or JPG, max 1 MB, displayed as a rounded square
Workspace banner: 1600×340 px (4.7:1 ratio) — PNG or JPG, max 1 MB
Custom emoji: 128×128 px — PNG or GIF, max 64 KB, transparent background recommended
Shared images in channels: no resolution limit, but Slack auto-compresses previews for files over 5 MB; max 10 MB per file (free plan), 1 GB total storage (free plan)

Profile Photo

Your Slack profile photo appears in the sidebar next to direct messages, in channel member lists, in the message header, and on your profile page. Slack always crops it to a circle, so square images work best. The photo is displayed at sizes ranging from 36 px (compact sidebar) up to 72 px (DM header) depending on the view.

Recommended upload size: 512×512 px
Aspect ratio: 1:1 (square)
Formats: PNG or JPG
Max file size: 1 MB
Display: always cropped to circle

Tip: crop your photo to 1:1 before uploading using the image cropper — this lets you control exactly which part of the image appears inside the circle instead of relying on Slack's automatic crop.

Workspace Icon

The workspace icon is the small logo that appears in the Slack sidebar and in the app switcher. It identifies your organization to members across multiple workspaces. Slack displays it at 34–68 px but stores the full uploaded image, so uploading at 512×512 px keeps it sharp on high-DPI screens.

Recommended upload size: 512×512 px
Aspect ratio: 1:1 (square, auto-cropped to rounded square)
Formats: PNG or JPG
Max file size: 1 MB

Tip: use a version of your logo that is just the icon or mark — no taglines or fine text. At 34 px, detailed text becomes completely unreadable. A simple symbol on a solid or white background works best.

Workspace Banner

The workspace banner is a wide decorative image displayed at the top of the sidebar on desktop. It gives your workspace a branded look without interfering with functionality. Slack displays the banner at roughly 220 px tall on desktop, but the source image should be 1600×340 px to look crisp at all window sizes.

Recommended size: 1600×340 px (approximately 4.7:1 ratio)
Formats: PNG or JPG
Max file size: 1 MB
Safe zone: keep important elements (logos, text) within the center 1000 px — edges may be clipped on narrow screens or certain OS themes

Use the image resizer to crop and scale your banner image to exactly 1600×340 px before uploading.

Custom Emoji

Custom emoji let your team react with branded images, inside jokes, or company-specific symbols. Slack is strict about emoji file size — the 64 KB limit is easy to exceed with animated GIFs.

Size: 128×128 px
Formats: PNG (static) or GIF (animated)
Max file size: 64 KB
Transparent background recommended
For animated GIFs: keep frame count low and limit colors to stay under 64 KB

Sharing Images in Channels

When you share images directly in a Slack channel or DM, Slack generates an inline preview. There is no hard resolution limit when uploading files, but Slack automatically compresses image previews for files over 5 MB. The original file is still stored and downloadable — only the in-chat preview is compressed.

For crisp channel previews: keep JPEGs under 3 MB and PNGs under 5 MB
Screenshots and diagrams: use PNG for lossless quality — compression artifacts can make text unreadable in JPEG previews
Max file size per upload: 10 MB (free plan), 1 TB per file (paid plans)
Total free storage: 1 GB per workspace (free plan)

If your images are too large for the free storage limit, use the image compressor to reduce file size before uploading — you can typically cut file size by 60–80% without visible quality loss.

Tips for Better Slack Images

Pre-crop profile photos to 1:1: Slack's automatic circle crop centers on the full image, which can cut off faces in landscape photos. Crop manually first.
Workspace icons: icon only, no taglines: at the sizes Slack displays, a full logo with text becomes illegible. Export just the symbol or mark.
Banner safe zone: keep important content in the horizontal center — the leftmost and rightmost ~300 px may be obscured on narrow windows.
Mobile preview: Slack on mobile may crop or scale images differently from the desktop app. Always preview your workspace branding on both platforms before rolling out to the team.
PNG vs JPG for emoji: PNG with a transparent background usually looks cleaner in dark mode and against colored message backgrounds. Avoid white backgrounds on emoji unless intentional.

How to Resize Images for Slack

Identify which Slack asset you need — profile photo, workspace icon, banner, or emoji
Crop to the correct aspect ratio using the image cropper (1:1 for profile and icon, 4.7:1 for banner)
Resize to the target dimensions using the image resizer
If the file is over the size limit, reduce it with the image compressor
Upload directly in Slack — no third-party tool required