Make a PDF smaller while keeping the text crisp and the images readable. The preview shows you the exact resulting size at three quality levels before you download.
Large PDF files are difficult to email, slow to upload, and frustrating to share. PDFwarp's compression tool reduces file size while preserving readability — and shows you the exact output size at every compression level before you download.
For 90% of use cases, Medium compression is invisible to the eye and cuts file size 30-60%. Reach for High only when a specific size cap is forcing your hand — like a 5MB email attachment limit.
If your PDF is mostly text with no images, expect 5-15% reduction at most. The gains come from downsampling embedded images, and there aren't any to downsample.
If PDFwarp can't produce a smaller file than the original, we return the original instead of a bloated copy. You won't waste a daily conversion on a non-improvement.
If you plan to run a scanned PDF through AI Scan to Text, don't compress first — aggressive compression destroys the character edges that OCR relies on.
Compression runs through Ghostscript's pdfwrite engine with three hand-tuned presets. High uses the /screen profile for maximum reduction. Medium downsamples images to 150 DPI with bicubic resampling at moderate JPEG quality — the sweet spot where screens can't tell the difference. Low only touches images above 400 DPI and re-encodes them gently, preserving print quality. All three subset fonts and deduplicate repeated images.
The size preview runs the same three Ghostscript commands as the actual compression — the numbers you see are real output sizes, not projections. Whatever the preview shows for Medium is byte-for-byte what clicking Compress at Medium produces.
Already-optimized PDFs can inflate under recompression, so PDFwarp compares output to input and returns your original if nothing helped. And when Ghostscript can't shrink a file — typically images already below its downsampling thresholds, as phone-scanner apps produce — a second engine takes over and re-encodes each embedded image directly at the level's JPEG quality. Two engines, and you get whichever result is smaller.
It depends on content. Image-heavy PDFs can shrink 60-80%. Text-only PDFs may only shrink 5-15%.
Image-heavy PDFs (scans, photos, presentations) compress dramatically — often 60-90%. Text-only PDFs compress less, typically 5-15%.
This can happen if your PDF is already optimally compressed. PDFwarp detects this and returns the original file instead.
High: smallest file, lower image quality. Medium: balanced. Low: minimal compression, original quality preserved.
At Medium compression, the difference is virtually invisible on screen. High compression may reduce image sharpness slightly.
Yes. All text, links and structure are preserved. Only image resolution may be reduced on High compression.
You must remove the password first using our Unlock PDF tool, then compress.