Compress PDF to 2 MB

When a PDF under 2 MB helps

• Long scanned documents such as contracts, statements or theses
• Photo-heavy reports, catalogs and slide decks saved as PDF
• Email attachments that should open quickly on a phone

Slide decks and reports exported to PDF can carry photos with far more pixels than the page shows. The tool scales every image down to the page at the chosen resolution, so such files have a lot to gain.

If the file is still over 2 MB at the strongest setting, the text, fonts and drawings alone may be larger than the limit. Split the PDF into parts, or share a link to the file instead of attaching it.

Budget per page at 2 MB

The whole file has to fit into 2,000,000 bytes (16,000,000 bits), pages, images, fonts and structure together. In a scan, the page images take nearly all of that. A single Letter page at 150 dpi, the Medium level, is 2,103,750 pixels, which leaves 7.61 bits per pixel at 2 MB.

The last two columns show the highest resolution on the tool's list at which a full scanned Letter page still gets that many bits per pixel. Quality bands from section 4.5 of Gregory Wallace's paper on the JPEG standard, which rates color images of moderate detail; he notes that results vary with the content, so read them as a cautious guide for scans. A4 is about 3% larger than Letter.

The steps the tool tries for 2 MB

The tool does not guess from a table: it compresses the real file and measures it. These are its ten steps, from mild to strong, with the pixel size of a full Letter page at each resolution and the number of such page scans that 2 MB holds at 0.5 bits per pixel.

Which PDFs fit in 2 MB

A one-page scan keeps 0.5 bits per pixel, which Wallace's guide rates good to very good, up to 300 dpi. Ten scanned pages still get there at 150 dpi. A PDF of text, like a letter or an invoice exported from a word processor, has no page images, so it fits or not depending on its fonts and text, and this tool copies those unchanged.

Some images stay as they are, because recompressing them would change them or gain nothing: images under 12 KB (12,288 bytes), black-and-white scans stored with fax-style compression (CCITT or JBIG2), JPEG 2000 images, images with a stencil or color-key mask, CMYK images, and flat graphics like logos and charts unless they shrink a lot in pixels. A recompressed image also has to be at least 10% smaller than the original, or the original is kept.

When 2 MB is out of reach

• If the PDF is already at or under 2 MB, the tool says so and you can send the original as it is.
• If it has no images the tool can recompress, it tells you right away that 2 MB is out of reach.
• If even the strongest step, 50 dpi at JPEG quality 30, stays above 2 MB, you see the smallest size it reached. When text, fonts and other parts alone take more than 2 MB, the message says how much. If that smallest version is at least 3% smaller than the original, you can still download it.

Then send fewer pages or split the document: cut out pages with Split PDF or drop the ones you do not need with Delete PDF Pages, and compress each part.

2 MB in bytes

Here 2 MB means 2,000,000 bytes. A system that counts in 1,024-byte units shows the same limit as 1,953.13 KB (1.907 MB); a file at or under 2,000,000 bytes is under both.

Gmail allows 25 MB per message for personal accounts. Attachments travel Base64 encoded, which turns every 3 bytes into 4 characters, so a 2 MB PDF takes about 2,666,668 bytes in the message. That makes 9 such files per message, whether 25 MB means 25,000,000 or 25 × 1,048,576 bytes. Counting the plain files instead gives 12 or 13.

Getting a PDF under 2 MB

Drop a PDF above. The target is already set to 2 MB. Press Compress PDF and the tool first runs its strongest step to check that 2 MB can be reached. If it can, it searches its steps for the mildest one that fits, from 300 dpi at quality 85 down, which takes three or four more runs. Text, fonts, links and form fields are copied unchanged. When the result uses 72 dpi or less, the tool asks you to zoom in and check that scanned text is still easy to read.

Need a different limit? One size down is 1 MB. Type any size into the target field, or use the PDF compressor with Low, Medium or High compression. To combine files first, use Merge PDF; to turn photos of a document into a PDF, JPG to PDF.

Sources

• Gmail Help: attachment size limits
• RFC 2045, section 6.8: Base64 content-transfer-encoding
• Gregory K. Wallace: The JPEG Still Picture Compression Standard, section 4.5 (copy hosted by the National University of Singapore)

Frequently asked questions