Compress an image to 50 KB

It depends on how many pixels it started with, and the tool decides per image rather than by rule. Something around 900 x 600 usually fits at its full size with quality to spare. A 1600 x 1200 photograph generally does not, and comes down to roughly 800 x 600 on the way. The result panel names the dimensions either way, so you never have to guess whether a resize happened.

Treat it as a ceiling you must stay below, which is what this tool aims at: it targets 50,000 bytes and keeps the result under that number, not at it. Forms are inconsistent about whether the stated figure is inclusive, and a file a few hundred bytes short of the limit is accepted everywhere while one a few bytes over may not be. The exact byte count is always shown.

Because half the bytes have to describe the same picture. The encoder spends what it has on the largest, most visible structures first, so fine texture - skin, fabric, foliage, small text - is what disappears as the budget shrinks. If both limits are acceptable to whatever you are uploading to, 100 KB will always look better; this page exists for when 50 is the number you were given.

Sometimes, and cropping is the lever that makes it likely. Trimming away background reduces the pixel count without touching the part of the image you care about, which often brings a photo under the limit at its remaining full resolution. Resizing deliberately to a smaller width before compressing has the same effect and gives you control over the number rather than letting the solver choose it.

Yes. Drop as many as you like and each one is solved independently against the same 50 KB ceiling, with its own verdict - because whether a given photograph can hold its dimensions at 50 KB depends on that photograph. Results download individually or together, and your images are never uploaded.