A 100 KB upload limit is a constraint, not a quality setting. A simple product photo and a noisy night scene can need very different encoding choices at the same dimensions. A useful batch workflow sets a byte target, tests representative images, and checks the actual results instead of promising that one slider value will fit every file.
Check what the receiving system measures
Read the upload form’s limit and accepted formats. Some systems use decimal kilobytes while others use a binary calculation or round their displayed sizes. Leave a little headroom when a file is close to the boundary, and confirm acceptance with a real upload to the destination.
Also check its minimum pixel dimensions. Reducing an image until it meets the byte limit is not useful if the receiving system rejects its width or height. Keep the original separately; a constrained export should not become your only copy.
Resize before searching for a byte target
A camera original with millions of unnecessary pixels makes a small byte budget harder to meet. Add Resize before compression and choose a realistic boundary for the final use. Fit inside keeps the whole composition; fill makes a fixed box by cropping overflow.
For example, test a 1200-pixel long edge for a small web illustration rather than compressing a 6000-pixel original directly. That is a starting experiment, not a rule for every document or marketplace. Inspect the details at the size people will actually see them.
Choose the format deliberately
JPEG and WebP can search a range of encoder quality values. WebP may be useful for modern web delivery, but only if the destination accepts it. JPEG is opaque: transparent parts need a background color.
PNG works differently. Its lossless mode preserves decoded pixels; a reduced palette can save bytes by using fewer colors. A photographic PNG can still be too large for a tight upload limit. Do not expect its quality controls to behave like a JPEG slider. Use the PNG compressor when transparency or sharp graphic edges matter, and inspect palette reduction carefully.
Start with the 100 KB preset
The 100 KB image compressor opens the online studio with the target configured. Import your supported files, confirm the output format, and enable the compression step. Review the selected image’s measured output size.
The target search may lower quality and, when required, reduce dimensions. It can still miss the requested budget. If the result remains too large, choose a smaller resize boundary, another accepted format, or less demanding content. If it fits but important text becomes unreadable, the byte target conflicts with your quality requirement; do not treat that as a successful export.
Understand keep-original mode
If the source already uses the selected output format, stays at its original dimensions, fits the target, and is smaller than the new encoding, keep-original mode can return it unchanged. This avoids a larger replacement but preserves the source metadata. Turn it off when a fresh encoding or removal of source metadata is part of your requirement.
Check the downloaded file, not just the proposed output settings. A source returned unchanged is not equivalent to a newly encoded JPEG or WebP.
Verify the complete batch
Review a flat-color image, a detailed image, and your largest source. After processing, check every result against the receiving system’s limit. Download a sample and test it in the real upload form before sending the rest.
For quality decisions beyond a strict upload budget, read compression without distracting blur. For the format decision, compare WebP and JPG. There is no single smallest acceptable file for every task; the destination and the image’s important details set the boundary.