Why is my image rejected when it is under 100KB?
A file-size limit is only one part of an upload form's requirements. A photo can be small enough and still have the wrong format, too few pixels, an unsupported shape, or a file size below the allowed minimum. Start with the exact error on the form and check the downloaded file, rather than the original picture.
Match your upload error to the next step
- File exceeds the maximum size: use the image compressor and enter the maximum stated by your form. For a 240 KB limit, enter 240; you do not need to reduce it all the way to 100 KB.
- Invalid width or height: open the image resizer with pixel controls. Set the form's file limit too, then choose exact dimensions only when both pixel values must match.
- Only JPG or JPEG allowed: select JPEG in the output format controls and download the converted image.
- File must be greater than 100 KB: this is a minimum-size requirement. A file under 100 KB will fail; check the full allowed range before compressing again.
- Cannot find the new file: follow the phone download and saving guide, then select the saved result on the upload form.
1. Check the actual byte count
A file manager may round the displayed size. “100 KB” on screen can conceal a file slightly over a portal's limit. This tool treats 100 KB as 100,000 bytes and measures the encoded result before offering it for download. Use the file's size in bytes when available; “size on disk” measures storage allocation and is not the upload size.
If the form asks for a smaller maximum, use the 50 KB compressor or 20 KB compressor. Renaming a picture to “photo-100kb.jpg” does not change its bytes.
2. Match the requested pixel dimensions
Kilobytes measure the file's data; pixels describe its width and height. Meeting one requirement does not guarantee the other. If a form requires an exact width and height, enter those dimensions using the tool's exact crop option and inspect the result. Cropping may remove parts of the picture, so check that the face or signature remains fully visible.
If only a minimum width or height is specified, keep that minimum while compressing. A smaller file that falls below the required resolution can still be rejected. The 100 KB resizing page explains how dimensions and file size interact.
3. Export a format the form accepts
A portal that accepts JPG may reject WebP or HEIC even when both are smaller. Select JPEG explicitly if the instructions require JPG or JPEG. Changing the filename extension alone does not convert the encoded image. JPEG output uses a white background for transparent areas; inspect signatures and logos after conversion.
Use PNG only when the receiving form accepts it. Preserving PNG's lossless encoding within a small byte allowance may require fewer pixels, particularly for photographs.
4. Check for a minimum size too
“Between 20 KB and 50 KB” is different from “under 50 KB.” A simple signature can naturally encode below the minimum. Use the size-range setting when the form specifies both boundaries. This compressor does not append meaningless padding to pretend a file has the requested size. If the range cannot be reached with your selected dimensions and format, it reports that limitation.
5. Select the new download and inspect its contents
Save the completed result, open it, and then choose that file on the upload form. A similarly named camera original can be easy to select by mistake. Check readability, orientation, background and framing before submitting. A successful compression result confirms the selected size settings; it does not certify compliance with an application's photo-composition rules.
To see how a smaller allowance affects dimensions, compare our measured downloads at four file-size limits.
Cannot find the processed photo? See how to save compressed images on iPhone or Android for download folders, sharing and ZIP extraction.
If the upload still fails
Read the receiving website's current instructions and try its recommended browser. A connection problem, expired login or unavailable upload service cannot be fixed by compressing the picture again. Share the error message with that site's support team without posting identity documents publicly.
Ready to prepare a new copy? Open the 100 KB image compressor. Images are processed on your device, and the original remains unchanged.