A PDF that is too large to email, too slow to upload, or that eats up storage space is one of the most common file frustrations. This guide covers every free method for reducing PDF size, ranked from fastest to most effort-intensive.
Why Is My PDF So Large?
Before compressing, it helps to understand what is making your PDF large. The main culprits:
High-resolution images embedded in the PDF — this is the most common cause by far
Embedded fonts — especially when the full font file is included rather than just the characters used
Layers, form fields, and annotations that add invisible data
Multiple pages with complex graphics or vector artwork
Metadata, thumbnails, and version history baked into the file
A PDF consisting only of text is rarely large — it is almost always images causing the problem.
Method 1: Online PDF Compressor (Fastest, Recommended)
Best for: most users. Gets the job done in under 30 seconds with no software or technical knowledge required.
Go to the compressor. Visit convertfloor.com/tools/compress-pdf in any browser.
Upload your PDF. Drag and drop or click to browse. Files up to 100MB accepted.
Choose compression level. Three options are available: High Quality (smaller reduction, best appearance), Balanced (recommended for most use cases), Maximum Compression (smallest file, some quality reduction in images).
Download. Click Download. Your compressed PDF is ready.
How much will it reduce the size? Results vary by what is in the PDF:
Image-heavy PDFs: 50–80% size reduction typical
Text-only PDFs: 10–30% reduction
Scanned PDFs: 30–60% reduction depending on resolution
Method 2: Reduce Image Quality Within the PDF
If maximum compression is not enough, the next step is targeting the images themselves. When a PDF is created from a Word or InDesign document, images are often embedded at full print resolution (300+ DPI). For screen and email use, 72–150 DPI is more than sufficient.
How to do this: when creating the PDF from Word, choose File → Save As → PDF → Options → change 'Bitmap resolution' to 96 or 150 DPI instead of the default 220 or higher. If you only have the finished PDF (not the source file), use our Maximum Compression mode which re-samples images automatically.
Method 3: Split the PDF
If a PDF is large because it contains many pages, splitting it into smaller parts is more effective than compressing it. A 50-page document sent as five 10-page files will be easier to email and often serves the recipient better.
Use ConvertFloor's PDF Split tool: convertfloor.com/tools/pdf-split. You can split by page range, extract individual pages, or split every page into its own file.
Method 4: Remove Unnecessary Elements
Some PDFs contain hidden data that adds size without being visible:
Embedded fonts: if the font is a standard system font, it does not need to be embedded
Metadata: author name, creation date, revision history
PDF layers: if the document was created in design software, multiple layers may be present
Form fields: even unfilled form fields add to file size
Advanced PDF tools (Adobe Acrobat, PDF Expert, Sejda) let you remove these elements individually. For most users, running the file through our compressor first achieves a similar result.
How to Reduce PDF to Under 1MB
Getting a PDF under 1MB is achievable for most documents but may require combining methods:
Run through Maximum Compression first
If still over 1MB, split the document into sections and compress each part
If still over 1MB, the document may have very high-resolution images — consider re-exporting from the source file at lower DPI
Last resort: convert specific pages to images (JPEG) and re-build the PDF from those images
How to Compress PDF on Mac
Our online compressor works in Safari and Chrome on Mac — no download required. There are also two Mac-native options:
Mac Preview (Limited Results)
Open the PDF in Preview → File → Export → Quartz Filter → Reduce File Size. Warning: this often produces poor quality results and sometimes increases file size. Use only as a last resort or for low-quality prints.
ColorSync Utility (Better Than Preview)
Applications → Utilities → ColorSync Utility → Filters. More control than Preview but still limited. For best results, use our online compressor.
How to Compress PDF on iPhone
Open Safari on your iPhone and go to convertfloor.com/tools/compress-pdf. Tap the upload area, select your PDF from the Files app, choose a compression level, and tap Download. The compressed PDF saves to your Files app. No app installation needed.
Frequently Asked Questions
Q: How do I reduce PDF file size for free?
A: Visit convertfloor.com/tools/compress-pdf, upload your PDF, select a compression level, and download the compressed file. Free with no signup or daily limits.
Q: How much can I reduce a PDF file size?
A: It depends heavily on the content. Image-heavy PDFs typically compress by 50–80%. Text-only PDFs compress by 10–30%. Scanned PDFs fall in the middle at 30–60%.
Q: Why is my compressed PDF still too large?
A: The PDF likely contains very high-resolution images, many pages, or both. Try splitting the document using our PDF Split tool, or use Maximum Compression mode if you used a lower setting previously.
Q: How do I reduce PDF file size without losing quality?
A: Use the High Quality compression setting in our tool — it achieves size reduction primarily through removing invisible metadata and re-encoding text streams, with minimal impact on visible image quality. Avoid Maximum Compression if preserving image sharpness is important.
Q: How do I decrease the size of a PDF on a Mac?
A: Use ConvertFloor in Safari (no download needed) for the best results. Mac Preview's built-in Quartz filter is available but often produces worse results than online tools.
Q: Can I compress multiple PDFs at once?
A: Yes. ConvertFloor supports batch uploads. Upload multiple PDFs and download each compressed version separately.
Summary
Fastest method: convertfloor.com/tools/compress-pdf — upload, choose compression level, download. Free, no limits, no signup. For very large files, combine with PDF Split at convertfloor.com/tools/pdf-split.
Related tools:
PDF Split — convertfloor.com/tools/pdf-split
PDF to JPG — convertfloor.com/tools/pdf-to-jpg (convert pages to images)
PDF to Word — convertfloor.com/tools/pdf-to-word
Delete PDF Pages — convertfloor.com/tools/delete-pdf-pages