Switch the size unit to KB, type your target (say 200 KB), and the optimizer auto-tunes JPEG quality (and downscales only if it must) to land at or under the limit.
Upload forms are the usual culprit. Visa portals, job applications, and government websites cap photos at 100 KB, 200 KB, or 500 KB, while a single phone or DSLR photo can be 5 to 30 MB. Trying to hit a number by eye is painful. A camera-club member on the Adobe support forum described the exact problem: 60 JPGs at up to 2 MB each that all had to come down to about 0.7 MB for a web gallery, with no clear way to do it in one pass.
In Batch Picture Resizer the width and height fields include a KB unit. Pick it, and only the target-weight field stays. The program tries JPEG quality levels in memory, and downscales from the original only if quality alone cannot reach the goal, so it writes the file just once. There are presets for 20, 50, 100, 200, 500 KB and 1, 2, 5 MB. It outputs JPEG in this mode, which is the right format for a photo upload anyway. For a KB-only walkthrough, see our reduce image size in KB guide.
Can you compress images without losing visible quality?
Yes, within reason. At JPEG quality 80-85 the difference is invisible to the eye while the file drops 50-70%. "Lossless" keeps every pixel but saves less; "visually lossless" lossy saves far more.
"Compress without losing quality" is a fair promise as long as you know what it means. Truly lossless compression keeps every pixel identical and still trims the file, but only by stripping hidden overhead, usually 5 to 25%. The bigger wins come from lossy compression tuned so the loss stays below what your eye can see. Image-tooling vendors like Tinify make the same distinction.
How much smaller do files actually get?
For typical photos, expect a 50 to 80% reduction at sensible quality settings, more if you also convert to WEBP. A 6 MB JPEG often lands near 1.5 MB with no obvious change on screen. The honest catch: re-compressing an already-compressed JPEG a second time costs quality for almost no extra saving, so optimize from the original when you can.Lossy vs lossless compression: which should you pick?
Lossless for logos, screenshots, and line art where every pixel matters. Lossy for photos, where a small, invisible quality trade buys a much smaller file.
The choice is not about good versus bad. It is about the image. Photographs have so much detail that the eye never registers a careful lossy pass, so lossy (JPG or lossy WEBP) is the right call and the savings are large. Graphics with sharp edges, flat color, or text (logos, UI screenshots, diagrams) can show artifacts under lossy compression, so lossless PNG or WEBP keeps them clean. A good optimizer keeps that choice per batch instead of forcing one mode on everything.
Why does my PNG barely shrink?
Because PNG is always lossless, so a "compress" pass only saves a little. To shrink a photo saved as PNG, convert it to JPG or lossy WEBP instead.
This trips up a lot of people. They run a heavy 8 MB PNG through optimizer, expect it to halve, and watch it drop by maybe 10%. That is normal. PNG stores every pixel exactly, so there is little to remove without changing the format. If the PNG is actually a photo, convert it to JPG or lossy WEBP and the file collapses. Keep PNG only where you need transparency or pixel-perfect graphics. When you do need to keep the PNG and its transparency, a palette-based compress PNG tool can still cut its size right in the browser. A batch tool that converts formats handles this in the same run.
Batch Picture Resizer
