Compress PDF
Reduce your PDF size by up to 80% without noticeable visual quality loss. Free, no signup.
.pdf · up to 2 GB
When to compress a PDF
Compress PDF: less weight, same content
Email attachments
Gmail and Outlook have 25 MB limits. Compress your PDF to send it as an attachment without issues.
Platform uploads
HR portals, government platforms, and e-learning systems have file size limits.
Web optimization
Downloadable PDFs on your site load faster and consume less CDN bandwidth when compressed.
Storage savings
Reduce space occupied in Google Drive, Dropbox, or local drives by PDF collections.
How it works
Three steps, no hassle
Upload your PDF
Drag or select the PDF you want to compress. Works with any PDF: scanned, generated from Word, presentations, forms.
Select the compression level
Choose between high quality (moderate compression), balanced (best size/quality trade-off), or maximum compression (minimum size). You'll see an estimated resulting size.
Download the compressed PDF
Compare size before and after. Download your compressed PDF. Identical visual appearance, much smaller size for emailing or uploading to platforms.
FAQ
Got questions?
A PDF can contain several types of content with different compression properties. Images are typically the heaviest component and the most compressible: high-resolution images embedded in the PDF (300 DPI or more) can be reduced to 72–150 DPI for web use without noticeable visual loss on screen. Text and vector graphics in PDF are already highly compressed with algorithms like Flate/zlib or LZW and offer little additional reduction margin. PDF content streams can be repacked and optimized by removing duplicate objects, unreferenced resources, unnecessary metadata, and old document versions.
It depends on the content. A PDF with many high-resolution photographic images can be reduced by 70–85% while maintaining acceptable web quality. A pure text PDF generated from Word without images has little additional compression margin — perhaps 10–20% through internal structure optimization. A high-resolution scanned PDF (300 DPI or more) can be compressed by 60–80% by reducing to 150 DPI without significant visual loss on screen. Typical reduction for mixed PDFs in balanced mode is 40–60%.
It depends on the selected compression level. In high-quality mode, compression is primarily structural (removing redundant data, optimizing streams) and visual quality is virtually identical to the original. In maximum compression mode, images are significantly reduced in resolution and JPG compression, which can produce visible artifacts on text over images or highly detailed photographs when zoomed. For screen use and email, the difference is generally imperceptible. For high-quality printing, use high-quality mode or no compression.
There are several reasons: fully embedded fonts instead of subsets can add unnecessary megabytes; hidden high-resolution images in headers, logos, or watermarks; preview thumbnails embedded in metadata; very extensive XMP metadata streams; and previous document revisions not removed (PDFs that have been edited and saved multiple times accumulate old versions). Compression and optimization removes all this superfluous data.
Compression requires read access to the PDF content. PDFs protected with an open password cannot be compressed without the password. PDFs with permission restrictions but without an open password can be compressed in many converters, although some respect author restrictions.
Most web services have limits between 50 MB and 200 MB per file. For very large PDFs, desktop tools like Ghostscript (a free, open-source command-line tool) or Adobe Acrobat Pro offer unlimited size processing and batch compression options for multiple files.
Compress PDF: how to reduce size without losing quality and why it matters
PDF compression is one of the most demanded operations in document management, and the reason is purely practical: unoptimized PDFs can be disproportionately large. A 30-page report generated from Word with some images can weigh between 5 and 50 MB depending on how it was created. The same report after compression can weigh 1–5 MB. This difference matters when the document must be sent by email (Gmail, Outlook, and most email clients have a 25 MB attachment limit), uploaded to document management platforms with size limits, stored in cloud services with storage quotas, or served as a download on a website where download time impacts user experience and CDN transfer costs. The internal structure of the PDF format (ISO 32000) allows multiple size optimization strategies, and understanding which to apply depending on the case is key to getting the best result.
The most compressible component of a PDF is images. When a PDF is created from a scanner, camera, or software that embeds high-resolution images, each image can occupy several megabytes. PDF image compression can be performed in two dimensions: resolution reduction (downsampling, from 300 DPI to 150 DPI for web use) and increased JPG compression ratio (from JPG 90% to JPG 60%). The combination of both techniques can reduce image sizes by 80–90% with minimal visual loss for screen use. Tools that use Ghostscript — the open-source PostScript/PDF processing engine developed since 1988, maintained by Artifex Software — apply this process through predefined profiles: screen (72 DPI, maximum compression), ebook (150 DPI, balanced), printer (300 DPI, high quality), and prepress (300 DPI with color management, for professional printing). Adobe Acrobat Pro uses a similar system with its Reduce File Size and PDF Optimizer settings.
For organizations managing large volumes of PDF documents, systematic compression is an infrastructure maintenance operation. A digital archive with 100,000 unoptimized PDF documents can occupy several terabytes; the same optimized archive can occupy 200–500 GB, with corresponding savings in cloud storage costs (Amazon S3, Google Cloud Storage, Azure Blob Storage) and transfer. Document management systems like SharePoint, Alfresco, or OpenText Content Manager incorporate automatic PDF optimization modules as part of their ingestion pipelines. In the healthcare sector, where digital medical records include diagnostic images stored in PDF for distribution, efficient compression has a direct impact on IT operating costs. Convertir.ai allows this compression to be performed immediately for individual documents, directly from the browser, without needing to install Ghostscript, Adobe Acrobat, or any other specialized software.