PDF Tool
Compress PDF Files
Make a PDF smaller, losslessly or by re-encoding its images. Choose Low, Medium, High, Custom or a target size, see what the level does to a page before you compress, and compare any page of the result with your original before you download.
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How to Compress PDF
Upload your PDF
Drop your PDF into the upload area or click to browse.
Choose a compression level
Pick Low (lossless), Medium, High, Custom or Target size. On a computer the page shows the level's effect beside your original straight away; on a phone, press Preview quality.
Compress, compare and download
Press "Compress PDF". Compare any page of the result with your original and check the sizes before and after, then press "Download PDF".
Features
- Five settings: Low (lossless), Medium, High, Custom and Target size
- Side-by-side quality preview
- Any page compared with your original at Fit, 100% or 200%
- A warning when a page comes out badly wrong
- Before/after file size comparison
- An image the file repeats is stored once, at every level
- Images with a soft mask are re-encoded with their transparency kept
- Custom image resolution (DPI) and JPEG quality controls
- Grayscale conversion option
- Target size mode: fit under a KB or MB limit
Frequently Asked Questions
How much will my PDF be compressed?
It depends on what the PDF holds. Only images can be made much smaller: a scanned or photo-heavy PDF shrinks a lot at Medium or High, while a PDF that is mostly text shrinks little at any level. At every level, including Low, an image the file holds several identical copies of is stored once. Before you compress, the preview shows what the chosen level does to the images on one page; afterwards you see the exact sizes before and after.
Will compression reduce visual quality?
Low keeps every image exactly as it is. Medium and High re-encode images as JPEG, and reduce any image drawn on the page sharper than 150 DPI (Medium) or 96 DPI (High) to that resolution. On a computer the page beside the controls shows the chosen level next to your original as soon as you pick it; on a phone, press Preview quality. After compressing you can compare any page of the result at up to 200%, and if a page has come out badly wrong — dark, inverted or with parts missing — you are warned before you download.
What is the Custom mode?
Custom lets you set the JPEG quality (1–100); an image resolution in DPI, so that an image drawn on the page sharper than that is reduced to it; and grayscale for images. An image whose size on the page cannot be worked out — one only an annotation draws, for example — keeps its resolution. Fonts and text are never removed at any level.
Does this work for scanned PDFs?
Yes. A scanned page is an image, which is what compression can shrink. Images in a form the tool does not re-encode — in CMYK, with a colour palette, or with a stencil mask, for example — are left exactly as they are; an image with ordinary transparency (a soft mask) is re-encoded with that transparency kept, and the result says so for each page.
Can I compress a PDF to a specific size?
Yes — choose Target size and enter a limit in KB or MB. The images are compressed only as far as needed to fit. A PDF that is mostly text may not reach a very small limit; when that happens you are told, and given the smallest version.