Understanding KB and MB When Preparing Images for Slack Messages
Size limits are written in kilobytes and megabytes, and the units trip people up. 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.
Understanding KB and MB When Preparing Images
One megabyte is roughly 1000 kilobytes, and some systems count 1024. If a limit says 100 KB, aim a little under, such as 95 KB, to be safe.
For Slack messages, a target of 500 KB is a comfortable default. Our results panel shows the exact size of each compressed file so you can confirm it before uploading.
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
- Always keep the original file and compress a copy.
- Use JPEG for photos and PNG for logos and line art.
- Name files descriptively with lowercase words and hyphens.
- Check the result on a phone, where most people will see it.
FAQ
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.
Is WebP accepted for e-learning courses?
It depends on the platform. JPEG is the safest choice when you are not sure.
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
- 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.
- Quick Guide: Compress JPEG for Slack Messages in 30 Seconds
Short on time? Here is the fastest route.
- Aspect Ratios to Use for Landing Pages
Aspect ratio is the shape of the image, and the wrong one leads to awkward crops.
- Upload Errors and File Size Limits for Restaurant Menus Online
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