Quick answer
Set the target to 500 KB. The tool repacks the PDF first without changing it; if that is not enough it redraws the pages at 150, 110, 96, 72, 60 and 48 dpi and stops at the first step that fits. At 96 dpi an A4 page has 0.89 million pixels, so 500 KB allows about 4.60 bits per pixel for one page, and extra pages share the same limit.
| Resolution | A4 page in pixels | Bits per pixel available |
|---|---|---|
| 150 dpi | 1241 × 1754 | 1.88 |
| 110 dpi | 910 × 1286 | 3.50 |
| 96 dpi | 794 × 1122 | 4.60 |
| 72 dpi | 595 × 842 | 8.18 |
| 60 dpi | 496 × 701 | 11.78 |
| 48 dpi | 397 × 561 | 18.39 |
These figures are computed with the same formulas as the Compress PDF to 500KB above. Change the inputs in the tool to see your own result.
Compress PDF to 500KB makes a PDF small enough for email attachments and upload forms that stop at half a megabyte. It starts with a lossless repack, which is often all a typed document, invoice or exported report needs, and lowers page image quality only if the file is still over the limit. At 500 KB, a handful of scanned pages stays comfortably readable. Everything runs in your browser, so contracts, statements and forms are never sent to a server.
Made for everyone. Typical uses:
A six-page PDF exported from a design tool at 2.4 MB, mostly because of embedded photos, commonly lands between 300 and 480 KB. A bank statement made of text may drop only a little in the lossless step and already fit.
Scans of more than about eight pages may not reach 500 KB without a visible loss of sharpness. When the image steps are used, text stops being selectable and searchable. Encrypted files must be unlocked first, and very large files over 150 MB are not accepted.
Accuracy: Files are processed with established open-source libraries and tested with real PDFs. Open the result and check it before you send or publish it.
Expert Tip
Before compressing, remove pages you do not need with the Split PDF tool. Every page you drop frees room for the others, and it is usually a better trade than lowering the quality of all of them.
Half a megabyte is a practical limit for many things people send every day. Some mail gateways and shared inboxes refuse large attachments, many forms cap uploads around this size, and a file under 500 KB opens quickly on a slow mobile connection. It is also a size at which typed documents almost always fit, and a handful of scanned pages stay clear.
The tool at Compress PDF to 500KB is built for that case: it protects text where it can, and lowers image quality only as far as the limit requires.
A PDF can be heavy for reasons that have little to do with the page count. Embedded photos at print resolution, a scan stored as an uncompressed image, several full fonts embedded for a few characters, and a design exported with hidden layers all add weight. A report with four small screenshots can weigh 3 MB if each screenshot is stored at the size of the original screen capture.
This is good news, because it means a lossless repack and a moderate image reduction often cut such files by half or more with no visible change on a screen.
The two methods suit different documents. The lossless step keeps your text, fonts and vectors exactly as they are, so the file stays searchable and prints sharply; it helps most with exported documents. The image step is for scans and photo-heavy files: it keeps everything you can see but turns pages into pictures.
The tool tries the lossless step first and only moves to the image step if the file is still over 500 KB. If you need text to stay selectable, check the result: a note under it tells you whether a lossless repack was enough.
Think of 500 KB as a budget to be shared by the pages. If a portal wants a short list of documents in one file, remove anything not required with Split PDF, reorder the rest, and compress the final result once rather than compressing each part and then merging, which would repeat the quality loss. If you receive a locked file, unlock it with Unlock PDF first, because compression cannot read protected files.
For images that will be placed in a PDF, shrinking them first with the Image Compressor is more efficient than shrinking the finished PDF.
Open the compressed PDF, zoom to 100 percent and read a few lines of the smallest text. Check signatures and stamps, which can lose edge sharpness first. Since the whole process runs in your browser, you can repeat it with a different target in seconds without anything being uploaded.
A few situations come up again and again with this size, and each has a simple answer.
Pick the right method for scans, slides, photos and text documents, hit email and upload limits, and stop big PDFs at the source with better scan and export settings.
How much a PDF can shrink, why scans are the problem, how many pages fit under each size limit, and how our tool reaches a target without ruining the text.
How to combine JPG and PNG images into a single PDF in order, choose A4 or Letter pages, set margins, and keep the file small with the right quality setting.
Explore more in PDF Tools, read the guides and articles, or see how we test our tools.
Reduce PDF file size to a target you set, or with lossless optimizing or a smaller image-based copy.
Best for getting a PDF under the size cap of a job, visa, school or government upload form
Extract specific pages from a PDF file.
Best for sending only the relevant pages of a long report or contract
Combine multiple PDF files into one.
Best for combining a cover letter, CV and certificates into one application PDF
Shrink a PDF to under 200 KB for application portals.
Best for attaching a CV and a certificate to a job application form
Shrink a PDF to under 1 MB with the least quality loss.
Best for submitting an assignment or thesis chapter to a portal with a 1 MB cap
Convert PDF files to editable Word documents.
Best for extracting text from PDF documents for editing