Reduce quality before dimensions
For JPG and WebP, the tool first searches encoding quality at the original dimensions. It only scales pixels down when the target cannot otherwise be reached.
PNG requires a different decision
PNG is lossless and can have a high minimum size. If a transparent PNG cannot reach the target, the tool explains the trade-off before offering WebP or JPEG conversion.
Start with the cleanest original available
Use the camera original, scanner output, or highest-quality export rather than a file that has already been compressed several times. Each JPEG re-encode can add ringing, blocks, and softened edges. Returning to the original gives the quality search more real detail to preserve at the requested KB target.
Crop, rotate, correct exposure, and remove unnecessary margins before reducing file size when those visible edits are required. File-size compression should be the final preparation step, after the image already has the dimensions, aspect ratio, and background expected by the destination.
Choose the format before choosing a quality level
JPG is normally efficient for portraits, products, and scanned photographs. WebP can achieve compact results when the receiving system accepts it. PNG is appropriate for transparency, signatures, logos, and sharp text, but its lossless structure makes some small maximums impossible without reducing colors or dimensions.
Do not rename an extension to satisfy a portal. The actual encoded format must match the filename. When a format conversion would remove transparency or change compatibility, make that decision explicitly and preview the result over the background where it will be used.
Understand the browser quality search
For JPG and WebP, the worker encodes candidates at different quality settings while keeping the original width and height. It chooses the largest valid candidate at or below the target because that candidate generally preserves the most information. Any small remaining gap is padded to produce the exact byte count.
If no full-size candidate fits, the search tries progressively smaller dimensions and repeats the quality process. This ordering avoids discarding pixels when a moderate encoding adjustment is sufficient. An unreachable-target message means the browser could not create a valid image within the requested size, not that processing silently failed.
Review quality and leave a safe upload margin
Open the download at 100% zoom and inspect faces, hair, gradients, small print, signatures, and high-contrast edges. Compare it with the original and confirm that required dimensions remain valid. Keep the source so another attempt never starts from an already compressed result.
This site uses decimal KB, where 100KB equals 100,000 bytes. If a portal publishes only a maximum and does not define its units, select a target slightly below the cap. Then confirm the extension, exact byte count, dimensions, aspect ratio, filename, and visible appearance before safely uploading the final result to the receiving system.