Privacy Tips When Compressing Images for Slack Messages
Many online compressors upload your images to a server. That is not always necessary. Shared images live in workspace storage and get re-downloaded by every viewer, so smaller is kinder to everyone.
Recommended settings for Slack messages
| Setting | Starting point |
|---|---|
| Format | JPEG (WebP where accepted) |
| Width | about 1600 px on the long edge |
| Quality | 78 |
| File size | 500 KB or less |
These are practical defaults. If the platform or form you are using publishes its own limits, follow those instead.
Privacy Tips When Compressing Images
TheCompressJPEG processes images in your browser. Nothing is sent anywhere, which matters for IDs, documents and family photos.
Before sharing images for Slack messages, also check the picture itself: addresses, licence plates and documents in the background can reveal more than you intend.
Step by step with TheCompressJPEG
- Open the compress JPEG to 500 KB tool, or the main compressor for custom settings.
- Drop in your image. Nothing is uploaded; it is processed in your browser.
- Set the maximum width to 1600 and the target size to 500 KB.
- Press Compress, check the result and download it.
Quick tips
- Write a size limit slightly below the stated maximum to leave a margin.
- Process private images locally rather than uploading them to unknown servers.
- Crop out distractions so pixels go to the subject.
- Use WebP where it is supported and you control the page.
FAQ
Is WebP accepted for e-learning courses?
It depends on the platform. JPEG is the safest choice when you are not sure.
What size should an image be for e-learning courses?
A practical default is about 1600 pixels wide and 200 KB or less, unless the destination states its own limits.
Can I compress images for e-learning courses without uploading them?
Yes. TheCompressJPEG runs entirely in your browser, so your images never leave your device.
Wrapping up
For Slack messages, the reliable recipe is simple: resize to around 1600 pixels, compress at quality 78 or to a 500 KB target, and check the result before you upload. Keep the original so you can always start again.
Related guides
- Understanding KB and MB When Preparing Images for Slack Messages
Size limits are written in kilobytes and megabytes, and the units trip people up.
- Aspect Ratios to Use for Slack Messages
Aspect ratio is the shape of the image, and the wrong one leads to awkward crops.
- Converting HEIC to JPEG for Slack Messages
iPhones save photos as HEIC by default, and not every site accepts it.
- Upload Errors and File Size Limits for Slack Messages
An upload error is frustrating when the message is vague.
- Understanding KB and MB When Preparing Images for Landing Pages
Size limits are written in kilobytes and megabytes, and the units trip people up.
- Converting HEIC to JPEG for Restaurant Menus Online
iPhones save photos as HEIC by default, and not every site accepts it.