Key takeaways
- Aim for 970 KB, 1.90 MB or 4.75 MB as shown by the tool, so the file passes whether a portal counts megabytes in 1,000,000 or 1,048,576 bytes.
- High quality renders pages at about 144 DPI, Balanced at about 108 DPI and Small file at about 72 DPI, with JPEG quality of 85%, 70% and 50%.
- Always rerun the original at a stronger level instead of compressing the compressed copy, which adds blur without saving much more space.
- Text-only PDFs are usually small already, and image-based compression removes selectable text, so re-export CVs and editable files from the source app instead.
To compress a PDF to under 1 MB, 2 MB or 5 MB, open Compress PDF, start with the Balanced level and check the new size. If it is still over the limit, run the original file again at Small file. If even that is too big, remove pages you do not need or split the file into two uploads. No compressor can promise an exact size, so the method is to aim a little under the limit and adjust.
First, check what "1 MB" means to the portal
Upload forms do not all count a megabyte the same way. Some treat 1 MB as 1,000,000 bytes and others as 1,048,576 bytes. Our Compress PDF tool counts in the larger unit and shows anything under 1 MB in KB, so a file it reports as 1000.0 KB is 1,024,000 bytes, which a strict 1,000,000-byte limit would reject.
The safe habit is to leave a margin:
| Portal limit | Aim for, as shown by the tool | In bytes |
|---|---|---|
| 1 MB | 970 KB or less | about 993,000 |
| 2 MB | 1.90 MB or less | about 1,992,000 |
| 5 MB | 4.75 MB or less | about 4,981,000 |
Those targets sit under both definitions. Your computer may show a slightly different number again: Windows File Explorer counts in 1,024-byte units, while a Mac's Finder counts in 1,000-byte units.
What the three compression levels actually do
The tool re-renders every page as a JPEG image, then rebuilds the PDF from those images, all inside your browser. Each level sets two things: how many pixels each page gets, and how hard the JPEG is squeezed.
| Level | Approximate resolution | JPEG quality | Pixels on a US Letter page |
|---|---|---|---|
| High quality | 144 DPI | 85% | about 1.9 million |
| Balanced | 108 DPI | 70% | about 1.1 million |
| Small file | 72 DPI | 50% | about 0.5 million |
High quality pages carry roughly four times the pixels of Small file pages, and Balanced about 2.25 times. That is why the jump between levels is large.
Two side effects matter before you submit anything. Text on the compressed pages becomes part of a picture, so it can no longer be selected, copied or searched. And at Small file, 10-point body text is only about 10 pixels tall. It stays readable on screen, but small print, footnotes and thin table lines start to look soft.
Work out a budget per page
Divide the limit by the number of pages to see how much room each page has:
| Target | Pages | Budget per page |
|---|---|---|
| 1 MB | 5 | about 200 KB |
| 1 MB | 10 | about 100 KB |
| 2 MB | 10 | about 200 KB |
| 5 MB | 20 | about 250 KB |
| 5 MB | 50 | about 100 KB |
A tight budget across many scanned pages points straight to the Small file level, or to cutting pages. A generous budget across a few pages means Balanced or High quality will probably fit. The tool shows the before and after size the moment it finishes, so testing is quicker than guessing.
A routine that hits the limit
- Run Balanced on the original. Check the new size against the targets above.
- Still over? Run Small file on the original, not on the compressed copy. Squeezing an already compressed file adds blur without saving much.
- Still over? Remove pages. Blank backs of double-sided scans, duplicate cover sheets and pages the portal did not ask for all cost space. Delete PDF Pages has buttons that fill in every even or odd page number, which helps with blank backs.
- Still over? Split the upload. If the form accepts more than one file, Split PDF cuts the document into page ranges you can upload separately.
- Last resort: rescan. A scan made at a lower resolution, or in grayscale instead of colour, starts smaller than any compressor can make a huge original.
What to expect from text-only PDFs
A PDF exported from Word or Google Docs stores its words as text, which takes very little space. A long report with no photos is usually small before you touch it. Check the size first, because there may be nothing to do.
If you do run a text-only file through Compress PDF, it will often say the file is already compact and produce nothing. That is deliberate. Turning a page of crisp text into a picture usually makes it bigger, and the tool never hands back a file larger than the one you gave it.
When a text PDF is still over the limit, the weight is coming from images or embedded fonts inside it. Our explainer on why PDFs get so large covers the causes. The better fix is usually to export the file again from the source app with a smaller-size option, rather than compressing it.
When not to compress at all
Some uploads are hurt by image-based compression, even when the size fits:
- CVs and job applications. Many hiring systems read the text in your CV. A compressed copy has no text layer, so a parser may see nothing. Re-export the CV from Word or Google Docs instead.
- Files you still need to edit or convert. Run PDF to Word or any text extraction on the original, then compress the final version last.
- Forms with fillable fields. The rebuilt file keeps the look of each page, but fields, links and bookmarks do not survive.
For the general case of shrinking a PDF for email, our guide to reducing PDF file size for email and uploads covers the basics. This one is for when a form tells you an exact number.
Frequently asked questions
No compressor can promise an exact size, because the result depends on what is inside each page. Run the Balanced level, check the new size, and move to Small file if it is still over. Aim for 970 KB as the tool shows it, which passes limits counted in either 1,000,000 or 1,048,576 bytes.
Divide 2 MB by the page count to get a budget per page. Ten pages gives about 200 KB each, enough room to try Balanced first. Fifty scanned pages gives about 40 KB each, which points to Small file plus removing pages you do not need. Test, because the size shows instantly.
The pages may be large scans, or there may simply be too many of them for the budget. Try the Small file level on the original, delete blank or unneeded pages, or split the file into two uploads. If the PDF is mostly text, the size is coming from embedded images or fonts instead.
It can. The tool turns each page into a JPEG image, so text loses some crispness, especially at the Small file level, where 10-point text is about 10 pixels tall. Body text stays readable on screen, but footnotes and fine lines soften. Text also stops being selectable or searchable after compression.
Avoid image-based compression for a CV if you can. Many hiring systems read the text inside the file, and a compressed copy has no text layer left. Export the CV again from Word or Google Docs, which usually produces a small file, and only compress it if there is no other way to fit.