Compress Image to 4MB
Hit the 4MB upload cap used by Slack free-tier uploads and many document management systems.
Compress to Target Size
Compress images to a specific file size in KB.
Drop images here
or click to select files — multiple files for batch processing
4MB is the free-tier attachment ceiling on Slack and a common cap on document management systems and content platforms. Source photos from modern phones often land between 3 and 8MB, so many files hover just above the limit.
ImageMint's Target Size tool trims the last megabyte without touching visible quality — a binary search across JPEG/WebP quality converges in a few seconds.
How to Compress
- 1
Upload Your Image
Drop the source file. Multi-megapixel originals work fine.
- 2
Set Target to 4MB
Enter 4096 (KB). WebP is recommended when the platform accepts it.
- 3
Download the Result
Upload the compressed file to Slack or your document system.
Tips
- Slack free-tier attaches are capped at 4MB per workspace member — paid plans lift this.
- For archival, 4MB JPEG at quality 90 is indistinguishable from the original at typical viewing distances.
- Downscale dimensions first if the source is over 6000px — you'll get the same final size at higher effective quality.
FAQ
Is 4MB still too large for Slack?
No — 4MB is the exact free-tier per-file limit. Files at or just under 4MB upload successfully.
Will image quality suffer?
Not visibly. 4MB is generous enough for near-lossless compression of most photos.
Can I batch-compress multiple 4MB files?
Yes. Drop multiple files and they'll all be processed in parallel.
Other Target Sizes
Compress to Any Target Size
ImageMint's Target Size tool finds the optimal quality automatically.
Open Target Size Tool →