Quick answer
Set the target to 1 MB. 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 1 MB allows about 9.42 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 | 3.85 |
| 110 dpi | 910 × 1286 | 7.17 |
| 96 dpi | 794 × 1122 | 9.42 |
| 72 dpi | 595 × 842 | 16.74 |
| 60 dpi | 496 × 701 | 24.13 |
| 48 dpi | 397 × 561 | 37.66 |
These figures are computed with the same formulas as the Compress PDF to 1MB above. Change the inputs in the tool to see your own result.
Compress PDF to 1MB brings a PDF under one megabyte, the limit used by many university portals, assignment systems, job sites and email gateways. Most PDFs that are slightly over a megabyte fit after a lossless repack or a light quality reduction, so the result usually looks very close to the original. The tool lowers page image quality only as far as needed and stops as soon as the file fits. It runs locally in your browser and nothing is uploaded.
Made for everyone. Typical uses:
A 1.6 MB report with a few screenshots frequently fits after the first step. A ten-page scan of 6 MB generally ends between 600 KB and 950 KB at about 96 to 110 dpi, which is clear for reading on a screen.
A very long scan, such as fifty pages, will not fit under 1 MB without becoming hard to read. Pages with large photos lose some fine detail. Image steps turn pages into pictures, so the text is no longer selectable, and a PDF that cannot get smaller is reported honestly instead of being returned larger.
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
If a portal says "maximum 1 MB", aim a little lower, such as 900 KB, by typing a custom size of 0.9 MB. Some upload systems count in decimal megabytes and a file that is exactly at your limit can still be refused.
One megabyte is the most generous of the usual upload limits, and it is usually enough to keep a PDF looking almost exactly like the original. Universities use it for assignments, job sites for portfolios, banks for document uploads, and many email systems for attachments. A file that is slightly above the limit, say 1.3 to 2 MB, typically needs only a light touch.
That is the case Compress PDF to 1MB is designed for: change as little as possible, and stop as soon as the file fits.
It helps to know what makes up a megabyte. A typed page is typically 20 to 60 KB. A scanned page at reading quality is around 80 to 150 KB. A page with a full-width colour photo can be 500 KB or more. A 1 MB budget therefore holds an assignment of ten to twenty typed pages, about six to ten scanned pages, or a short brochure with a few photographs.
Comparing these numbers with your file tells you quickly whether the limit is easy, tight or impossible without cutting pages.
Portals do not always count the way your computer does. Some use decimal megabytes (1,000,000 bytes) while your system shows binary (1,048,576). A file that shows as 1.0 MB on your device can be refused. For that reason the safe target is a little below the stated limit.
A long scan is the usual cause. A fifty-page scan of 15 MB will not get below 1 MB without every page becoming hard to read. The remedies are the same as for smaller limits: cut pages you do not need with Split PDF, scan again in grayscale at 150 dpi, or upload in parts. If you can choose the format, a PDF made from the original text with Text to PDF or exported from a document editor is smaller than any scan.
To reuse the pages as pictures instead, PDF to JPG renders them as images you can resize and re-assemble.
The compression runs in your browser, and no copy of your document is sent to a server. For contracts, loan papers and student records, that matters more than saving a few seconds. If you need a lower limit later, the same page lets you pick 500 KB or any custom size.
These are the questions people ask most when a file sits just above the line.
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.
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 500 KB for email and forms.
Best for emailing an invoice, statement or contract to a client whose server limits attachments
Remove password protection from PDF files.
Best for archiving a statement you protected yourself without retyping the password each time
Convert PDF pages to JPG images.
Best for extracting a single page from a PDF as an image to share or embed