Compress an Image to Under 150 KB
A 150 KB ceiling, reached by searching quality rather than guessing it.
Who asks for a 150 KB limit
CMS upload caps and forms that ask for 'under 150 KB' to reduce storage costs.
What 150 KB buys you in pixels
A workable ceiling for a 150 KB photograph is around 1100 pixels on the long edge at a quality that still looks like a photograph rather than a mosaic. That figure is empirical: it comes from how much high-frequency detail survives compression at that byte budget, and it moves up for images with large flat areas and down for images full of foliage, fabric or hair.
| Long edge | What to expect at 150 KB |
|---|---|
| Under 660 px | Comfortable — the quality search will settle in the high end of the range |
| 660–1100 px | Workable — expect mid-range quality, check gradients for banding |
| Over 1650 px | Resize down first, or the target cannot be met without visible damage |
At 150 KB you can keep fine detail in a 1100-pixel image. This is the smallest size at which a full-page document scan usually remains comfortably readable on screen.
The smallest ceiling that keeps a document scan readable
A full-page scan needs enough resolution for text to stay crisp, which is a different demand from a photograph: fine black strokes on white are the worst case for JPEG. At 150 KB with an 1100-pixel long edge a page of ordinary body text remains comfortably readable on screen — the same page at 30 KB does not.
Why this runs in your browser
The file is read from your disk by the browser, decoded with the browser's own codecs, and re-encoded in this tab. No upload request is made, nothing is queued on a server, and closing the tab leaves no copy anywhere. You can verify this in the network panel while it works.
How to use it
- Drop the image on the drop zone.
- Set the target size to 150 KB.
- Let the quality search run — it reports the quality level it settled on.
- Check the resulting file is at or under 150 KB, then download.
Worth knowing
- Target 150 KB permits roughly 1100 pixels on the long edge at photographic quality.
- The quality search encodes repeatedly and keeps the highest quality that fits.
- Image content, not just dimensions, determines how far the quality can be pushed.
- Switching to WebP at the same 150 KB budget usually looks visibly better than JPEG.
Limitations
- Very tight targets require resizing as well as compressing — compression alone has a floor.
- Downscaling permanently discards pixels; keep the original as your archive copy.
- Re-compressing an already-compressed file spends quality twice.
- Some portals also check pixel dimensions and file format, not just the byte count.