What 100 KB is for
A 100 KB limit turns up where a photo is shown a bit larger than a form thumbnail, or where the upload is a document rather than a face:
- Profile photos on job sites, professional networks, school and club systems.
- A photo on a CV or résumé, so the document itself stays small enough to email.
- Supporting documents on application portals — a photographed certificate, a payment receipt, a page of an ID — where each file has its own limit.
- Listings and support tickets that cap each attachment, and older content systems.
Photos at 100 KB
One hundred kilobytes is 800,000 bits. A typical phone photo at that budget comes out roughly 1,400 to 1,900 pixels on the long side at a clean quality — more than enough to fill a phone screen and to look sharp in a profile circle at any size a website shows it. If you only need it small (a 400-pixel avatar, say), set Longest side at most above: the photo will fit at a higher quality and the file will often come out well under 100 KB.
Scanned and photographed documents at 100 KB
A document behaves differently from a photo. Text is sharp black edges on a flat background, which a JPEG can store cheaply — but only if the background really is flat. A page photographed on a desk, in yellow light, with a shadow across it, has a background full of gradients and grain that eats the budget, and the text ends up blurred to pay for it.
- Photograph the page flat, from directly above, in daylight, without your phone's shadow on it.
- Crop to the page edges so no desk is left in the frame. On iPhone, the Notes app's document scanner (and the scanner in Files) does this and evens out the background for free.
- Compress here and zoom into the result: small print should still be readable. If it isn't, the tool had to shrink the page too far — split a two-page document into two files if the portal allows.
When the limit is per form, not per file
Some portals allow 100 KB for everything you attach. Then the budget is shared: three documents at about 30 KB each, for example. Use compress to KB with your own number for each file.
Honest limits
The verdict under the result describes compression damage at the result's size; the dimensions tell you how much was scaled down. A dense document, such as a full page of small print, may only fit at dimensions where the smallest text stops being legible — the tool can't tell text from texture, so check it yourself before you upload. The result is a JPEG with no EXIF data.
Other sizes: 50 KB for application-form photos, 200 KB for web images and detailed scans.