You are about to submit a job application, upload your enrollment documents, or attach proof to a government portal, and the page throws an error: "File exceeds the maximum allowed size". Your PDF is 9 MB and the limit is 2 MB. It is one of the most common frustrations when you build a document bundle from phone photos and scans.
This guide covers why a PDF ends up so large, how to bring it down to the size you need without rescanning everything, what you actually give up when you compress hard, and what to do when compression alone is not enough.
Why your PDF is so large
A PDF that contains only text, like a letter written in Word and exported, usually weighs a few hundred KB. The real bulk comes from images, and most documents people upload to portals are exactly that: photos or scans of ID cards, utility bills, certificates, receipts and transcripts.
Every scanned page is an embedded image. If you scanned it at 600 dpi, or shot it with a 12-megapixel phone camera, that single page can weigh 2 to 5 MB. Multiply by the ten pages in your application and you have a file no portal will accept.
- Scanning at 600 dpi or higher: print-shop resolution, unnecessary for any form submission.
- 12 MP or larger camera photos: 3 to 5 MB each before conversion.
- Pages stored as PNG or without internal compression.
- Color scans when grayscale or black and white would do.
Target size vs. fixed quality compression
There are two ways to compress a PDF. The first is picking a "fixed quality" setting: low, medium or high. The tool applies the same compression level to every image, and the output weighs whatever it weighs. If you are still over the limit, you try again with a lower setting, and keep guessing until it fits.
The second is compressing "to a target size": you tell the tool you need the file under 2 MB (or 5 MB, or whatever the portal demands) and it tunes the compression until it gets there. When you have a hard limit, this is the practical choice because it skips the trial and error.
fastpdfnow uses the target-size approach: you pick "under 2 MB", "under 5 MB" or another value, and the processing happens inside your browser. The file never leaves your device, which matters when the PDF contains your ID or personal data.
What you lose when you compress (an honest look)
Compression is not free. Under the hood, the tool lowers the resolution of the images and applies stronger JPG compression. At moderate levels the difference is barely visible on screen. At aggressive levels, scanned text can look blurry or show "noise" around the letters.
There is one thing many people do not realize: if your PDF had selectable text (because it came from Word, or because your scanning app ran OCR), some aggressive compression methods flatten pages into plain images. The document looks the same, but you can no longer select or search the text, and an automated system cannot read it either.
If the instructions ask for a "text PDF", or the file will go through a system that extracts data automatically, check the result before sending: open the compressed PDF and try to select a word.
How to pick the right target size
Start by reading the portal instructions or the call for applications. Many government portals, job boards, scholarship programs and universities set limits of 2 MB, 5 MB or 10 MB; some apply the limit per file, others to the whole submission. Do not assume: check the exact wording for your case.
Rule of thumb: compress to the largest size the portal accepts, not the smallest you can reach. If the limit is 5 MB and your file is 7 MB, choose "under 5 MB", not "under 1 MB". You keep as much quality as the rules allow, which matters for floor plans, tables with small figures, or certificates with a QR code.
Step by step: compressing your PDF with fastpdfnow
The whole thing takes under a minute and works from a computer or a phone, with nothing to install and no account to create.
- 1. Open fastpdfnow.com/compress in your browser.
- 2. Drag your PDF into the upload area, or tap "Select file" and pick it from your phone or computer.
- 3. Choose the target size: "under 2 MB", "under 5 MB" or another value, depending on what the portal requires.
- 4. Wait a few seconds while your browser processes the file. You will see the original size and the resulting size.
- 5. Download the compressed PDF and open it to confirm the pages are readable, especially numbers, signatures and stamps.
- 6. Upload it to the portal. If it still gets rejected, run it again with a slightly smaller target.
Common mistakes and what to do when it will not shrink
Sometimes compression does not reach the target, or the result looks rough. It is almost always one of these causes:
- You scanned at 600 dpi: the source image is huge, so compression has to be brutal. For forms and applications, 150 to 200 dpi is plenty.
- You used 12 MP or larger photos: a full-resolution phone photo is far more than any form needs. Lower the camera resolution or crop the photo to the document before converting.
- The PDF was already compressed: if someone compressed it earlier, the images have little left to give. Compressing twice mostly degrades quality without saving much space.
- The PDF has many pages: with 40 color scans, hitting 2 MB means about 50 KB per page, which is visibly degraded. Ask whether you can split the submission (/split) or send only the pages that are required.
The alternative: rescan properly from the start
If compression leaves the document unreadable or still does not reach the limit, the most effective fix is to regenerate the PDF with better settings. Scan at 150 or 200 dpi, in black and white or grayscale if the document has no meaningful color, and save straight to PDF. A ten-page bundle scanned this way usually weighs under 1 MB with no compression at all.
If you are using your phone, shoot in good light, frame only the document, and before converting with fastpdfnow.com/images-to-pdf, crop the photo to remove the background or lower the camera resolution in settings. For documents where color matters (a diploma, a colored seal), scan in color but at 200 dpi, then compress to the target size.
Key points
- A PDF gets heavy from its images, not its text. Scans at 600 dpi and 12 MP photos are the usual culprits.
- Compressing to a target size (for example, under 2 MB) avoids the guesswork of fixed-quality settings.
- Strong compression can blur text or turn it into a non-selectable image: check the result before you send it.
- Aim for the largest size the portal accepts, not the smallest possible, to preserve quality.
- If it will not shrink enough, rescan at 150-200 dpi in grayscale. It beats compressing twice.
Common questions
Does compressing a PDF delete or change the content?
It does not change the content, only the resolution and quality of the images. What may change is sharpness and, under heavy compression, whether text stays selectable. Always review the output file.
Is it safe to compress a PDF containing my ID with an online tool?
It depends on the tool. fastpdfnow processes the file inside your browser and nothing is uploaded to a server. With other tools, check their policy before loading personal documents.
Why does my 3 MB PDF not drop below 2 MB even after compressing?
It was probably already compressed, or it has many pages with little room left to shrink. Try a lower target, remove unneeded pages, or rescan at a lower resolution.
What scan resolution should I use for a form submission?
Between 150 and 200 dpi is enough for text to read clearly while keeping the file small. Use grayscale unless the colors in the document actually matter.
Written by the fastpdfnow team in Lima. We build the tools and write the guides from the questions people send us.