Compress a PDF to Under 1MB or 200KB for an Upload
Short answer
Divide your target by the page count to get a per-page budget, then apply the levers in order — downsample to 150 DPI, convert to greyscale, drop JPEG quality to 75%, and use black-and-white mode only when you need under about 50KB per page. Stop as soon as you are under the limit.
On this page
Government portals, job application forms and university submission systems nearly all impose a hard file size limit, and they are rarely generous. 2MB is common. 1MB is common. 200KB turns up more often than it should.
The frustrating part is that the form tells you the limit and nothing else. There is no indication of which setting to change or how far. So here is the method: work out a per-page budget, then apply the compression levers in a fixed order until you are inside it.
Start with a per-page budget
Divide your target by the number of pages. That single number tells you which settings you need before you touch anything.
| Target | 1 page | 5 pages | 10 pages | 20 pages |
|---|---|---|---|---|
| 200KB | 200KB/page | 40KB/page | 20KB/page | 10KB/page |
| 500KB | 500KB/page | 100KB/page | 50KB/page | 25KB/page |
| 1MB | 1MB/page | 200KB/page | 100KB/page | 50KB/page |
| 2MB | 2MB/page | 400KB/page | 200KB/page | 100KB/page |
Now compare that against what each setting realistically produces per page:
| Setting | Typical size per page |
|---|---|
| Plain text, no images | 10–30KB |
| Black-and-white scan, 150 DPI | 20–50KB |
| Greyscale scan, 150 DPI | 60–150KB |
| Greyscale scan, 200 DPI | 100–250KB |
| Colour scan, 150 DPI | 150–400KB |
| Colour scan, 300 DPI | 600KB–1.5MB |
A 10-page scan with a 1MB limit needs 100KB per page, which puts you squarely at greyscale 150 DPI. A 10-page scan with a 200KB limit needs 20KB per page, which only black-and-white mode will reach. Knowing that up front saves you three rounds of trial and error.
The levers, in order
Apply these in sequence and stop as soon as you are under the limit. Each one is lossy and irreversible, so there is no reason to apply more of them than you need.
1. Downsample the resolution
The biggest lever by a wide margin, because image data scales with the square of the DPI. Halving the resolution removes three quarters of the pixels.
- 300 DPI → 150 DPI: removes about 75% of image data. Still prints acceptably and reads cleanly on any screen.
- 600 DPI → 150 DPI: removes about 94%. This is where the enormous savings on scanned documents come from.
- 150 DPI → 96 DPI: removes about 60% more, but small print starts to break up. Only go here if you have to.
150 DPI is the working default. Use 200 DPI if the document has footnotes, handwriting or small print — or if anyone needs to run OCR on it later, since OCR is unreliable below 200 DPI.
2. Convert to greyscale
Scanners default to colour. Most documents are black text on white paper. Storing three colour channels for single-channel content wastes half to two-thirds of the file, and removing it costs you nothing visually because there was no colour information worth keeping.
Keep colour only when it carries meaning — highlighting, coloured charts, official stamps, or a blue-ink signature where that matters evidentially.
3. Drop the JPEG quality
The fine adjustment, worth 20–40%. 70–80% quality is indistinguishable on a document. Below about 60% you start seeing artefacts around letter edges, which is exactly where they hurt readability most.
4. Black-and-white mode (for the 200KB targets)
If you need to go below about 50KB per page on a scan, this is the only setting that reliably gets there. Black-and-white stores one bit per pixel rather than eight. A clean page of printed text can come out under 30KB.
The caveat is sharp: it renders anything with shading or photographs as harsh dithering. Use it only for typed or printed text on white paper. On a document with a photo ID or a greyscale logo, it looks broken.
Doing it in the browser
Our PDF compressor runs entirely on your device, which matters for exactly the documents that hit upload limits — passport scans, bank statements, payslips, signed contracts.
- Drop the PDF in.
- Choose Downsample pages to images.
- Set resolution to 150 DPI.
- Tick Convert to greyscale if the document is black and white.
- Leave quality at 75%.
- Check the resulting size against your target.
If it is still over, go back to the original — not the compressed output — and try 96 DPI or black-and-white mode. Compressing the compressed file compounds the artefacts for very little extra saving.
On a phone
If the document originated on paper, the best move is not compression at all. Re-scan it with the right settings and you never create the excess data.
- iPhone: Notes → new note → camera icon → Scan Documents. After scanning, tap the share icon and check the file size in Files.
- Android: Google Drive → + → Scan, or your phone’s built-in document scanner. Many Android scanners offer a quality or size setting in the save dialog.
A phone document scanner produces roughly 200KB per page. A photo of the same page taken with the normal camera app produces 3–5MB. The scanner mode crops to the page edges, corrects the perspective and saves in a document-appropriate mode — the difference is not subtle.
For PDFs already on your phone, our compressor works in a mobile browser without installing anything. Avoid the free app-store “PDF compressor” apps where you can: they upload your document to a server you know nothing about, and the documents people compress are rarely ones they would email to a stranger.
When one file simply will not fit
Some limits are not achievable without destroying the document. A 40-page colour brochure is not going under 200KB, and pretending otherwise just produces an unreadable file.
Three honest options:
Split it. Most forms that accept one 2MB file will accept four files of 2MB. Splitting copies pages without re-encoding, so the quality is untouched. If the form only accepts one file, check whether it accepts a zip.
Remove what is not needed. Cover pages, blank pages, duplicated appendices and scanned envelopes all take a full page of image data each. Deleting five blank scanned pages from a 20-page document removes a quarter of the file.
Share a link instead. If you are emailing rather than filling a form, a cloud link sidesteps the whole problem and is more reliable than fighting a size limit you cannot see.
What not to do
- Do not zip the PDF to shrink it. PDFs are already internally compressed. Zipping saves a few percent and some upload forms reject zip files outright.
- Do not compress repeatedly. Each pass degrades the images further. One pass with harder settings always beats two passes with mild ones.
- Do not go below 150 DPI on anything someone needs to read carefully, unless the alternative is not submitting it at all.
- Do not print-to-PDF as a compression method. It sometimes shrinks the file by accident, but it also rasterises text and destroys links, bookmarks and any searchable text layer.
- Do not delete the original until the upload has gone through and been accepted. Compression is one-way.
Check before you submit
Open the compressed file and zoom to 100% on the page with the smallest text. If you can read a footnote comfortably, the recipient can too. If reference numbers, dates or signatures have gone mushy, step back up one setting — a rejected submission costs far more than 200KB.
If you are compressing a scan specifically, compress a scanned PDF without making it unreadable covers the verification step in more detail. If the file refuses to shrink at all, PDF still too big after compressing explains why.