"The file size must not exceed 100 KB." You meet this sentence on exam registrations, scholarship applications, visa checklists, recruitment portals and many government services. The problem: a single page scanned with a phone usually weighs 1 to 3 MB, ten to thirty times more than allowed.
Ordinary compressors only offer "low", "medium" or "high" compression, so you try one, upload, get rejected and start again. There is a faster way: tell the compressor the size you need.
The quick method: compress to an exact size
- Open Compress PDF to a specific size.
- Select your PDF.
- Type the limit from the form in KB, for example 100, 200 or 300. For megabytes, multiply by 1000: 1 MB = 1000, 2 MB = 2000.
- Click Compress PDF and download the file. A message confirms that it is under your limit.
For the most common limits there are ready-made pages, already set to the right size:
| Limit on the form | Page to use |
|---|---|
| 100 KB | Compress PDF to 100KB |
| 200 KB | Compress PDF to 200KB |
| 500 KB | Compress PDF to 500KB |
| 1 MB | Compress PDF to 1MB |
| 2 MB | Compress PDF to 2MB |
What happens behind the scenes
Almost all the weight of a scanned PDF comes from its images. The compressor first tries gentle settings, then lowers the resolution and quality of the images step by step, and keeps the mildest setting that fits under your limit. Text and vector graphics are not touched, so they stay sharp.
When the limit is very small for the number of pages (for example, ten scanned pages in 100 KB), the pages are turned into compact grayscale images as a last step. If even that is not enough, you get the smallest possible file and a clear message, never a silent failure.
Five tips when the limit is very small
- Send only what is asked. If the form wants the first page of your diploma, remove the others with Remove pages before compressing.
- Scan in grayscale, at 150 dpi. Colour and 300 or 600 dpi multiply the size without making text more readable on screen.
- Crop the margins. A phone photo of a document often includes the table under it. Crop to the paper before making the PDF.
- One document per file. If the limit is a total for all uploads, divide it by the number of documents and compress each one to that size.
- Aim a little lower. If the form says "maximum 100 KB", a 95 KB file is safe even if the site counts 1 KB as 1024 bytes. Our tool already counts 1 KB as 1000 bytes for that reason.
Is the result still accepted and readable?
Yes. The output is a standard PDF that opens in every browser and PDF reader. Portals check only the file type and size, and the compressed file passes both. For readability, zoom in on the downloaded file before uploading: names, dates and stamps should be clear. If they are not, the limit is too small for the number of pages, so remove pages or split the document.