Bulk PDF Compressor (Many PDFs, One Size Limit)

About the Bulk PDF Compressor (Many PDFs, One Size Limit)

Exam, visa, court, bank and government upload portals often refuse any PDF over a fixed size, and a set of application documents is rarely one file. Drop all of them here, choose one rule — a size limit such as 100 KB, 200 KB, 500 KB or 1 MB, or a quality level — and every PDF is compressed with the same engines as the PDF Compressor and Compress PDF to Size: photos and scans are re-encoded and, where they are far sharper than needed, reduced in resolution, while text, fonts and vector drawings stay exactly as they are, sharp and selectable.

A table shows every file’s size before and after and whether it met the limit. Each result is reopened and checked before it is kept, a file that doesn’t get smaller keeps its original, and files that can’t reach the limit with their text kept as text say how close they got — retry them in greyscale or as page images if that is acceptable. Download everything as one ZIP with the original file names, plus a CSV report. Several files are compressed at once on your device; nothing is uploaded.

Common uses

• Getting a whole set of application documents under the per-file limit of an exam, job, visa, court or government portal.
• Shrinking a folder of scanned invoices, receipts or statements before archiving or emailing them.
• Making many photo-heavy reports small enough for a document system or an email attachment limit.
• Checking which of a set of PDFs already fit a limit, without changing those that do.

How each file is compressed

• Size limit: the settings run from lossless optimisation, through JPEG quality and resolution steps (85% at full resolution, then 300, 220, 175 and 150 DPI), down to 72 DPI at 30% quality. A binary search finds the sharpest step that fits, usually in six to nine full compressions of the file, then refines between the last two steps. Only results at or under the limit count as fitting. Limits count 1 KB as 1,000 bytes, so a file under “200 KB” passes portals that count 1 KB as 1,024 bytes too.
• Quality level: each file is compressed once with a PDF Compressor preset — Light (up to 220 DPI, 82% quality), Recommended (150 DPI, 70%) or Strong (110 DPI, 50%) — or only optimised without loss. A file that doesn’t get clearly smaller keeps its original.
• Greyscale turns the photos and scans that are re-encoded grey; coloured text and drawings, and images kept as they are, keep their colours.

Images are only reduced in resolution when they are more than 1.3 times sharper than a step’s limit, and never when the tool can’t tell how large they are drawn. Every result is reopened with pdf.js and its first page drawn before it is kept.

When a file can’t reach the limit

Fonts, text and vector drawings are already compact and can’t be shrunk without changing how they look, and some images are kept exactly as they are because re-encoding could damage them (transparent logos, CMYK print images, JPEG 2000, black-and-white fax-style or JBIG2 scans). When these alone are over the limit, the table says how small the file got. The smallest version reached goes into the ZIP’s over-limit folder, so it is never mixed up with files that fit.

Two stronger options are offered for those files only: - Greyscale makes colour photos and scans smaller. - Page images turn every page into a JPEG picture at the sharpest resolution that fits (200 DPI down to 72 DPI, measured on sample pages first). The text can then no longer be selected, copied or searched, and links and form fields are removed — check small print before sending such a file.

Several files at once

Files are compressed side by side in background workers: up to three at a time on a computer with enough processor cores, fewer on phones and on devices with little memory, and files of 60 MB or more on their own. The page stays usable while it works. Cancel stops at once: files in progress are left as they were, and files already compressed stay in the list. Results stay in this tab until you download them.

Limitations

• Up to 100 PDFs in one run, each up to 200 MB and 2 GB together; on phones, smaller batches are faster.
• Password-protected PDFs are listed as failed: unlock them first with Unlock PDF.
• Any change to a digitally signed PDF invalidates its signature; such files are marked in the results.
• Choosing a folder works in desktop browsers (and a dropped folder works everywhere); on phones, select the files instead.
• The first run downloads the PDF engines once, so it needs an internet connection.

Privacy

Everything happens in your browser. What you enter or open here is not uploaded or stored by MySmartCoPilot.