How to use the Compress PDF to 100KB tool
- Select your PDF or drop it onto the box. If it is already under the limit, the tool tells you straight away and you can upload the original.
- Pick the limit your form gives: 100 KB, 200 KB, 500 KB, 1 MB or 2 MB. For anything else, type the number of KB, for example 150 or 300, and press Set.
- Wait a few seconds while the tool tries different resolutions and quality levels. It keeps the sharpest version that is still under your limit.
- Tick Black and white pages if a target is hard to reach and colour does not matter, such as for a typed certificate or a printed form.
- Click Download. The file name ends in the size you chose, for example degree-100kb.pdf, so you can tell the copies apart.
Why forms ask for a PDF under 100 KB
Recruitment portals, university admission systems and visa sites store documents for thousands of applicants, so many of them set a hard limit per file. You will often see wording like “PDF only, maximum 100 KB” next to the upload button for a degree, a domicile certificate, an experience letter or a scanned ID card. Other portals allow 200 KB, 500 KB or 1 MB. The upload simply fails if your file is one byte over, and many portals do not tell you how big your file was.
A phone scan of a single page is often a few megabytes, so it may have to shrink by 90% or more. That is why a general “compress” button is often not enough: you need a result that is guaranteed to be under a number.
How the tool reaches an exact size
Each page is redrawn as an image at a chosen resolution and saved as a JPEG inside a new PDF of the same page size. The tool starts at 150 dpi, which is sharp on screen and good enough to print a form. It then searches for the highest JPEG quality that keeps the whole PDF under your limit. If even low quality is too big, it lowers the resolution step by step and searches again.
It stops at 50 dpi. Below that, the small print on certificates and bank statements becomes hard to read, and a file that passes the size check but cannot be read is worse than useless. In that case you get an honest message with the smallest size possible, and the choice to download it anyway.
How much space each page gets
Divide the limit by the number of pages to see what you are asking for. The PDF itself needs a little space for its structure; the rest is shared between the pages:
| Limit | 1 page | 3 pages | 10 pages |
|---|---|---|---|
| 100 KB | about 100 KB | about 33 KB each | about 10 KB each |
| 200 KB | about 200 KB | about 66 KB each | about 20 KB each |
| 500 KB | about 500 KB | about 166 KB each | about 50 KB each |
| 1 MB | about 1 MB | about 340 KB each | about 100 KB each |
The fewer KB each page gets, the lower the resolution and the softer the text. A full A4 page at 150 dpi is about 1240 × 1754 pixels; at 100 dpi it is about 827 × 1169. Colour photos, stamps and dark backgrounds take far more bytes than black text on white paper.
Tips for hitting a small target
- Send only the pages the form asks for. Drop blank backs and instruction sheets with Delete PDF Pages before compressing; it is the single biggest saving.
- Use black and white for typed documents. Removing colour also removes the faint yellow or grey tint many phone scans have.
- Crop the photo before making the PDF. If you are starting from phone pictures, crop away the table around the paper, then build the PDF with JPG to PDF.
- Photo and signature fields are different. Those usually want a JPG, not a PDF; use Compress Image to 20KB for them.
- No hard limit? If you only want a smaller file for email, Compress PDF with a quality level is simpler.
Typed a number like 150 because your portal says “between 50 and 150 KB”? The tool only guarantees the maximum. If a portal also has a minimum, check the size shown before you download.
Frequently asked questions
Will the PDF be exactly 100KB?
It will be at or just under 100 KB, never over. Upload forms reject files above the limit, so the tool aims for the closest size below it and spends the rest of the budget on sharpness.
Why can't the tool get my PDF down to 100KB?
Every page needs some bytes to stay readable. A two-page scan fits into 100 KB easily, but a 30-page document would leave about 3 KB per page, which is not enough for legible text. When a target is out of reach, the tool shows the smallest readable size instead of producing an unreadable file. Remove pages you do not need, switch to black and white, or ask whether the portal accepts the document in parts.
My PDF was made in Word and it is all text. Will this help?
Often not. A typed PDF from Word or Google Docs is usually small already, because text is stored as characters rather than pictures. This tool turns each page into an image, which can make a text-only PDF larger. If yours is already under the limit, the tool tells you to keep the original. If it is not, the size usually comes from embedded photos or fonts, and the tool can still help.
Can I still select or copy the text afterwards?
No. To hit a strict size, each page is saved as a compressed image, so text in the result cannot be selected or searched. Upload portals only need the document to be readable, so this is rarely a problem, but keep your original for your own records.
What is the difference between this and Compress PDF?
Compress PDF lets you choose a quality level and shows you the size you end up with. This tool works the other way round: you tell it the maximum size and it works out the quality for you. Use this one when a form gives you a hard KB or MB limit.
Is it safe for documents like my CNIC, Aadhaar, passport or degree?
Yes. The PDF is read and rebuilt by your own browser and is never uploaded to any server. You can even disconnect from the internet after the page has loaded and it will still work.
Does it work on a phone?
Yes, in Chrome, Safari, Edge and Firefox on Android and iPhone. Long PDFs take longer on a phone because every page is redrawn several times while the tool searches for the right size.
Guide by the ToolsYes team · Last updated