Compress PDF
Compare actual PDF sizes after structural optimisation or chosen image recompression.
Start with structural optimisation to retain page text and vectors. Image recompression and a full image-PDF rebuild are separate choices with different quality costs.
How to use it
- Load a PDF and choose structural optimisation first to retain original page text, vectors and supported document features.
- For image recompression, choose JPEG quality and expect detail loss within images, including existing JPEGs. Original page text and vector paths remain.
- Use image-only rebuilding only after accepting loss of selectable text, vectors, links, forms, annotations, bookmarks and document metadata.
- Enter the desired size in decimal kB and compress. The target is compared against actual bytes; it does not silently change the chosen method.
- Read the original, candidate and download byte counts and target status. Check small text and diagrams in the exported preview before downloading.
In one local synthetic capability fixture, a 1,024 × 768 image PDF shrank from 2,015,683 B to 94,974 B with explicit JPEG quality 70. This measured fixture demonstrates that path only; your document can shrink less, remain the same size or produce a larger candidate.
Details & limits
Up to 25 MiB input/output and 100 pages; 60 seconds per operation. Encrypted or digitally signed PDFs, XFA, embedded files, active document actions and nonstandard UserUnit scales are unsupported. Checked JPEG and unfiltered/Flate images are supported within decoded-resource limits; no inline images, JPEG 2000, JBIG2 or CCITT. No PDF/A, PDF/UA or signature-validity certification. Structure/image modes load the local qpdf 12.4.1 engine, about 2.25 MB. JPEG quality 30–95 for explicit image recompression. The image-only rebuild has stricter limits: 10 MiB input, 10 pages and 32 MP. Target 1–20,000 decimal kB, with no guaranteed reduction or target match.
Will every PDF meet the target, and what happens if compression makes it larger?
No target is guaranteed. Already optimised PDFs may not get smaller. The report shows the actual candidate size, and a non-smaller candidate is replaced by your original bytes for download. Structural optimisation preserves graphics; image recompression is lossy within images; image-only rebuilding has broader feature losses. No page is omitted to meet the target.