Write down the receiving service’s rules
Before compressing, note the allowed format, maximum file size, any minimum size, width and height, and crop or composition instructions. A limit copied from another application or an old article can be wrong for your form. ExactKB controls file size, output format and optional maximum dimensions. It does not validate every receiving service’s rules.
Choose the byte convention explicitly
The default uses 1024 bytes per displayed target unit. Turn the binary-size checkbox off to use 1000 bytes per KB. The tool displays the exact target in bytes. If a form says 100,000 bytes, select 100 with binary units off; a 102,400-byte budget is too large.
| Target | Decimal, 1000 bytes per KB | Binary, 1024 bytes per KiB |
|---|---|---|
| 20 | 20,000 bytes | 20,480 bytes |
| 50 | 50,000 bytes | 51,200 bytes |
| 100 | 100,000 bytes | 102,400 bytes |
| 200 | 200,000 bytes | 204,800 bytes |
| 500 | 500,000 bytes | 512,000 bytes |
For example, 99.8 KiB is approximately 102,195 bytes. It exceeds a 100,000-byte cap even though its rounded number appears below 100. A file of 99,800 bytes fits that cap. These are arithmetic examples, not measurements of a particular image.
A practical compression sequence
- Keep an untouched original. Crop in an image editor first if the form requires a particular shape.
- Select your image and choose an output format the destination accepts.
- Set the target and byte convention. Add a maximum dimension only if appropriate.
- Compress, inspect the preview and read exact bytes and dimensions.
- Download the new file, then choose that download when uploading. Do not accidentally select the original again.
If the form still rejects it
- “File too large”
- Compare exact bytes, not only the rounded KB label. Confirm the correct file was selected.
- “Unsupported format”
- A JPG extension alone is insufficient. Convert using the output selector; do not just rename a PNG or HEIC.
- “Invalid dimensions”
- Compare both output sides with the required minimum, maximum and aspect ratio. A longest-side limit does not crop to a square.
- “Image unclear”
- Inspect the original and result at normal size. Use a better original or a larger permitted budget; repeated compression cannot restore lost detail.
- The result is well below the limit
- An upper bound does not require exact equality. Extra padding would not improve the image. Check whether the destination also imposes a minimum.
For conversion issues, see HEIC troubleshooting. For a small target, open the 20 KB tool or 50 KB tool.
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