Compress JPEG to 100 KB

Upload portals that accept only JPEG are not being old-fashioned for its own sake. JPEG is the one photo format that every operating system, browser, document system and printer has read for decades, so a back office that receives thousands of files a day can process them without surprises. UPSC's 2026 CAPF examination notice, for instance, asks for the photograph and the signature in .jpg format, with the signature capped at 100 KB.

Those portals also check the file's content, not just its name. An iPhone photo renamed from .heic to .jpg, or a PNG screenshot with a new extension, is still HEIC or PNG inside and gets refused. This page avoids that: the output is encoded as a real JPEG every time, so the file passes a content check as well as the size limit.

You do not need a separate conversion step first. Running a PNG through the Image Converter and then compressing the JPG works, but it adds a lossy save in between. Here the decode, the format change and the size target happen in one pass, so the picture is encoded as JPEG exactly once.

Whatever you add is first decoded into plain pixels. A JPEG source is decoded too, which is why compressing a JPEG always means one more lossy step; the encoder cannot reuse the old data directly. The pixels are then written as a new JPEG at the highest quality that fits in 100 KB.

That single extra step is harmless when the source is a camera original, because the new file is made from the best data you have. It becomes a problem only with files that have been saved again and again by chat apps, editors and screenshot tools. Each of those passes left its own block pattern behind, and a fresh encode at 100 KB makes those patterns more visible, not less. When you have a choice of copies, pick the oldest, largest one.

Quality is the main dial. JPEG divides the picture into small blocks and stores each block's detail with more or less precision; a lower quality rounds more of that detail away. The tool searches the scale for the highest value that still fits in 100 KB and stops there. If even the lowest quality allowed, 40 by default, is too large, it reduces the pixel dimensions step by step.

Chroma subsampling is the second dial. JPEG can store color at half the resolution of brightness, which the eye barely sees in photos but notices in thin colored lines and small colored text. On Auto the tool chooses for you; set 4:4:4 for a scanned form with red stamps or blue ink, and 4:2:0 when every kilobyte counts.

Progressive JPG, on by default, orders the data so the picture appears blurry first and sharpens as it loads. It is usually a little smaller than baseline order and is read by every current browser and viewer. Location and camera metadata are removed unless you switch Strip metadata off.

Pixel size is the last lever. A JPEG of 1,200 pixels across reaches 100 KB at a much higher quality than one of 4,000, so if the form or page shows the picture small, set Resize first to that width. For sizes given in centimeters, Resize Image converts them, and the main Compress Image tool offers quality and percentage modes when a fixed size is not what you need.