Compress PDF under 500KB online — free
Shrink any PDF below 500KB while keeping text crisp. Perfect for tight upload portals, mobile data savings, and embedded web previews. Free, no signup.
500KB is one of the tightest practical caps you'll encounter — banking portals, certain visa applications, older school enrollment systems, and a surprising number of B2B procurement platforms still cap PDF uploads at half a megabyte. Most documents you'd want to send are 5-30 MB out of the box, so getting them under 500KB requires real compression, not a token reduction.
PDFOnly's compressor uses Ghostscript with content-aware downsampling. Text glyphs stay at full resolution (so the document remains crisp and readable), while embedded images are aggressively downsampled. For typical text-heavy documents — contracts, statements, forms — getting under 500KB is one click on the High preset. For image-heavy PDFs (scans, photographs, brochures), you may need to combine compression with OCR (run OCR first, then compress; the searchable text layer compresses better than the underlying image layer).
Frequently asked questions
Is 500KB realistic for every PDF?
For text-heavy documents (contracts, reports, statements): yes, almost always achievable on the High preset. For image-heavy PDFs (scanned books, photographic catalogs): possible but with visible quality loss. For PDFs that are already optimized, 500KB may be the floor — the original size minus ~10-20% is the realistic minimum.
Why do some upload portals require under 500KB?
Many of these portals are aging legacy systems built when 500KB was a sensible limit and never updated. They store all uploads on disk per record, so smaller files mean lower hosting costs at scale. Annoying but real.
Will text quality suffer?
No — we keep text rendering at full quality regardless of compression preset. Only embedded images are downsampled. Text stays selectable, searchable, and crisp on screen at any zoom level.