Plenty of upload forms refuse anything over 100 KB — government portals, exam registrations, job applications, older intranet systems. A photo from any phone made in the last decade is somewhere between 2 MB and 6 MB, so it is rejected before anything else about it matters, usually with an error message that does not tell you what to do next.
This page sets the converter to a 100 KB budget. Drop a photo in and it re-encodes the image repeatedly, searching for the highest quality that still fits, and only shrinks the picture if quality alone cannot get there. The work happens inside this browser tab — your photo is never uploaded, which is worth knowing when the thing you are compressing is a passport scan.
How it gets under the limit
Two levers exist and they are not equal. Re-encoding a JPEG at a lower quality setting discards detail the eye is bad at noticing, and it is reversible in the sense that you still have your original. Making the image smaller in pixels throws away detail permanently. So this tries the first one properly before touching the second.
It encodes the image at high quality, measures the result, and narrows in on the quality setting that lands just under 100 KB — typically eight or nine attempts, all of them in your browser and all of them fast, because the photo is only decoded once. If the lowest reasonable quality still overshoots, and only then, it scales the image down and searches again.
The result is that most photographs come out at their original resolution. A 750 KB iPhone photo lands just under the limit with every pixel still there. Images with a lot of fine detail — dense foliage, textured fabric, scanned text — compress worse and are the ones most likely to be resized.
What a photo looks like at 100 KB
Better than you would expect, for most subjects. A portrait or a document scan at 100 KB is perfectly legible and, at the size these forms display it, usually indistinguishable from the original. JPEG spends its budget on the parts of an image people look at.
Where it shows is in large areas of subtle gradient — a clear sky, a studio backdrop — which can develop faint banding, and in sharp high-contrast edges such as text over a photograph, which can pick up a soft halo. If the upload is a photograph of a person or a document, neither is likely to matter. If it is artwork you intend to print, this is the wrong tool and you want the original file.
The row under the converter tells you exactly what happened: the size before and after, the dimensions of the result, and whether the picture had to be resized to fit. If the target could not be reached at all, it says that too rather than handing you a file the form will reject.
Why the form rejected your photo in the first place
Size limits on upload forms are almost always about storage and bandwidth on the receiving end, set once when the system was built and rarely revisited. A limit that was generous for a 2008 digital camera is hostile to a 2026 phone, and the form has no way to explain that to you.
Format is the other common reason, and the two get confused. If the error mentions the file type rather than its size, the problem is that your phone saved a HEIC and the form wants a JPG — a different fix, and one this site also does.
If 100 KB is not the number you need
The "Fit under" control on this page offers 50 KB, 200 KB, 500 KB, 1 MB and 2 MB as well. Indian government portals in particular tend to ask for a photograph under 200 KB and a signature under 50 KB, often on the same form, and you can convert one then change the setting and convert the other without reloading anything.
Setting it back to "No limit" gives you an ordinary conversion at full quality, which is what every other page on this site does by default.
Frequently asked questions
Will my photo be resized?
Usually not. Quality is reduced first, and a typical phone photograph reaches 100 KB with its full resolution intact. Resizing only happens when the image is detailed enough that quality alone cannot get under the limit, and the result says so explicitly when it does.
Is my photo uploaded anywhere?
No. The decoding, the compression search and the download all happen inside your browser tab. You can confirm it by opening your browser devtools and watching the Network tab while you convert, or by disconnecting from the internet after the page loads — the converter still works.
How much quality do I lose?
As little as the budget allows. It searches for the highest quality setting that still fits rather than picking a fixed low one, so a photo that could have fitted at 95% quality is not compressed to 40% just because the limit is 100 KB.
What if it cannot reach 100 KB?
It hands you the smallest version it managed and labels it "could not reach that size", rather than pretending. That is rare for photographs and most likely on images that are mostly fine detail or noise. A PNG is the other case: PNG is lossless, so the only lever is resizing.
Does this work on an iPhone HEIC photo?
Yes. HEIC files are decoded in the browser and the result is a JPG, which is what the upload form wants anyway.