Compress PDF (reduce PDF file size)
Drop a PDF to make it smaller. Keep the text selectable, or set a size like 200 KB for an upload form. Nothing is uploaded.
Choose a PDF first.
Show your work
Compress a PDF to see every step and number.
Everything runs in this tab. To check, load the page, turn off Wi-Fi, and compress a file. Or watch DevTools > Network: nothing is uploaded.
Your PDF is compressed inside this browser tab and never uploaded. "Keep text" re-saves the file and recompresses its JPEG photos; text, links and form fields stay as they are. "Turn pages into images" replaces each page with a picture: text can no longer be selected or searched, and links, form fields, bookmarks and signatures are removed. Compressing a digitally signed PDF invalidates the signature. Your original file is never changed; keep it until you have checked the result.
How it works
Pick a mode and press Compress. "Keep text" cleans up the file and shrinks the JPEG photos inside it, so text, links and form fields still work. "Turn pages into images" redraws each page as a JPEG, which helps most with scans, and "Get under a size" starts with the gentlest method and steps down until the file fits.
Making a PDF from photos? Shrink them first with the JPG compressor or the image resizer, then combine them with JPG to PDF.
How we calculate it
The "Show your work" panel above lists every number after a run. This is what it covers.
- What is in the file. We add up the bytes of every image in the PDF. Under 20% images means mostly text, 20 to 60% is mixed, 60% or more is mostly images. This only picks the notice you see. It never changes the output.
- Strength. Light is 200 DPI at JPEG quality 80%. Recommended is 150 DPI at 70%; 150 DPI is Ghostscript's "ebook" setting. Strong is 100 DPI at 50%. Custom lets you pick 72, 100, 150, 200 or 300 DPI and quality from 10 to 95%.
- Lossless cleanup ("Keep text" and "Get under a size"). We remove unused objects, XMP metadata, page thumbnails and private app data, deflate any uncompressed streams, and save with object streams (ISO 32000-1 §7.5.7, §7.5.8). Nothing visible changes. On its own this usually saves 0 to 10%.
- Keep text: the photos. Only 8-bit RGB or gray JPEG images of 8 KB or more are recompressed. Images with transparency, CMYK colour or other formats are skipped, and the table says why. The largest page side in inches × DPI gives the size limit. An image is scaled down only if its long side is more than 1.5 times that limit (the Ghostscript and Distiller threshold). Example: a Letter page is 11 in tall, so at 150 DPI the limit is 1650 px and the threshold is 2475 px. A 4032 × 3024 photo becomes 1650 × 1238. The new image is kept only if it is at least 5% smaller.
- Turn pages into images. 1 pt = 1/72 in (ISO 32000-1 §8.3.2.3), so pixels = pt × DPI ÷ 72. A Letter page (612 × 792 pt) at 150 DPI is 1275 × 1650 px. Each page keeps its original size in the new PDF. On iPhone and iPad a page is capped at 16,777,216 pixels, and 40,000,000 elsewhere. If the cap lowers the DPI, the table says "capped".
- Get under a size. The target counts 1 KB as 1000 bytes. Attempts run in this order and stop at the first one under the target: cleanup only; keep text at 150 DPI, 70%; keep text at 100 DPI, 50%; then pages as images at 150, 100 and 72 DPI, picking the highest JPEG quality from 92% down to 40% that fits. Every attempt is listed with its real size.
- Result. Saved = 1 − new size ÷ original size, rounded to a whole percent. Example: 4,812,330 B to 1,203,082 B is 75% smaller, shown as 4.59 MB → 1.15 MB (sizes here use 1 KB = 1024 B). If no attempt is smaller than your file, there is no download.
Questions
How do I compress a PDF to 100 KB or 200 KB for an upload form?
Choose "Get under a size" and pick 100 KB or 200 KB, or type your own size. The tool tries the gentlest method first and only lowers resolution if it has to. It counts 1 KB as 1000 bytes, so the file also fits sites that count 1 KB as 1024. A long scan may not fit in 100 KB. If so, it tells you the smallest size it reached.
Why did my PDF hardly shrink?
PDFs exported from Word or similar apps are mostly text and fonts, which are already compact. Expect about 0 to 10% smaller. Big savings come from photos and scans. After you add a file, the tool shows how much of it is images, so you know what to expect before you press Compress.
Why can't I select the text after compressing?
Only "Turn pages into images" does that. Each page becomes a JPEG picture, so the text layer, links, form fields, bookmarks and signatures are lost. Use "Keep text" if you need to search, copy or click links. It only shrinks the photos inside the PDF.
Why do some PDFs get bigger after compressing?
Re-encoding images that are already well compressed can add bytes. Turning a text page into a picture usually makes it bigger too. This tool compares every result with your original. If nothing came out smaller, it says so and offers no download, so you keep your original.
Is my PDF uploaded?
No. The PDF is read and rebuilt inside this browser tab. To check, load the page, turn off Wi-Fi and compress a file. Or open DevTools, go to the Network tab and watch: nothing is sent.