Compress an image to 100 KB
The editor above is already set to a 100 KB limit. Drop in a photo and CropShrink searches the quality range for the best-looking export that still fits — you do not have to nudge a slider and keep checking.
Why 100 KB, specifically
Almost nobody wants a 100 KB image for its own sake. They want it because a form will not accept anything larger. The limit turns up in the same handful of places:
- Government and examination portals. Visa applications, university entrance systems, tax filings and recruitment sites very often cap photograph uploads at 100 KB, sometimes with a minimum as well.
- Job application forms. Applicant tracking systems frequently cap profile photographs and scanned documents.
- Older content management systems. A default upload limit that nobody has revisited since the site was built.
- Bulk email. Newsletter platforms recommend keeping images small so the message renders before the reader scrolls past it.
If your form states a minimum as well as a maximum — 20 KB to 100 KB is a common pair — check the output size readout after the search finishes. If it lands too low, raise the target a little; the search always takes the largest quality that fits, so it will use the headroom you give it.
How the editor finds the setting
Quality settings are not calibrated in kilobytes, and the relationship between the two depends entirely on the picture. A flat studio backdrop at quality 90 may be smaller than a forest at quality 40. So rather than guessing, CropShrink measures.
It encodes your image at quality 50, checks the size, and then halves the remaining range in whichever direction it needs to go — seven encodes to search a hundred settings. Every candidate is measured, not predicted, so the export you get always fits the limit. The panel tells you which quality it settled on, so you can see how much headroom the picture had.
One quirk worth knowing: at quality 100 the browser writes lossless WebP, which can be larger than quality 99. The search checks the size of every candidate rather than assuming bigger quality means bigger file, so this does not trip it up.
100 KB looks different at different sizes
A file size limit is really a budget of bytes per pixel. Spread the same 100 KB over more pixels and each one gets less. We measured it: the editor’s own resize and size search, run on our sample photograph — a detailed lakeside landscape, close to the hardest case a real photo presents — at seven widths:
| Pixels | Megapixels | WebP quality | JPEG quality | Result |
|---|---|---|---|---|
| 400 × 267 | 0.11 | 99 | 99 | No visible loss |
| 600 × 400 | 0.24 | 96 | 95 | No visible loss |
| 800 × 533 | 0.43 | 87 | 85 | No visible loss |
| 1000 × 667 | 0.67 | 76 | 70 | Clean, slightly soft |
| 1200 × 800 | 0.96 | 54 | 51 | Clean, slightly soft |
| 1600 × 1067 | 1.71 | 24 | 23 | Smeared; not usable |
| 1920 × 1280 | 2.46 | 12 | 15 | Smeared; not usable |
The pattern is the point: if 100 KB is hard to hit, the image is too big, not too detailed. A portrait against a plain background or a screenshot compresses far better than this landscape, so it can keep more pixels at the same quality.
When 100 KB cannot be reached
If even the lowest quality overshoots, CropShrink says so and tells you the smallest size your current dimensions can reach, rather than quietly missing the target or resizing your image without being asked.
The fix is almost always to reduce the dimensions. Switch on Resize, set the width to 1000 px — or 1200 px for a simpler picture — and run the search again. In the measurements above, a detailed photo that only fits at quality 12 at full width fits at quality 76 once it is 1000 px wide. If the form specifies exact pixel dimensions, use those; there is a page about resizing with more on choosing a width.
Cropping helps too, for a different reason: removing the parts of the frame you do not need removes their pixels from the budget entirely.
Other limits you may be given
The same control handles any target. Type the number the form asks for:
- 20 KB — signature and initial fields on official forms. Compressing to 20 KB measures how far a photo must shrink first.
- 50 KB — passport-style photographs on some portals. Compressing to 50 KB has its own page and measurements.
- 200 KB — a common ceiling for identity documents and certificates; see compressing to 200 KB.
- 500 KB — typical content management system upload gates; 500 KB is measured at camera sizes.
- 1 MB — a courteous ceiling for an email attachment or a forum post; see compressing to 1 MB.
More image tools
Every one of these is the same editor, opened for a different job — and all of them run on your device.
- Compress an imageShrink a photo for the web, an email or an upload form.
- Resize an imageChange the pixel dimensions with Lanczos3, Catmull-Rom or Mitchell.
- Crop an imageTrim to what matters, freeform or to a fixed ratio.
- PNG to WebPSame picture, same transparency, a fraction of the bytes.
- Remove EXIF dataStrip the GPS location, camera and serial number from a photo.
Or start from the full editor, which does all of it at once.