Compress PDF
Compress your PDF files to reduce file size while maintaining quality. Perfect for email and web sharing.
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PDF files only • Maximum 100MB file size
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Upload a PDF file to compress it and reduce its size while maintaining quality.
Privacy Protected
All compression happens locally in your browser. Your PDF files never leave your device.
Lightning Fast
Compress PDF files in seconds with our optimized compression algorithms.
Quality Balance
Smart compression maintains visual quality while achieving significant size reductions.
Multiple Compression Levels
Choose from three optimization levels to balance quality and file size perfectly.
Compress PDF in one sentence. Drop a PDF into the tool above, pick Light, Standard, or Strong, and download a smaller copy. Compression runs in your browser — files never leave your device. Free, no sign-up, files up to 100 MB.
What is PDF compression?
PDF compression shrinks the size of a PDF file by re-encoding images, removing redundant data, and trimming embedded fonts. The pages stay readable — only the bytes that don't carry visible information get reduced.
People compress PDF files for three reasons. First, email systems cap attachments at 20–25 MB, so a 40 MB report won't send. Second, smaller files download faster on slow networks and mobile data. Third, reducing PDF size cuts cloud-storage costs when you archive thousands of documents. The savings depend heavily on what's inside: scanned receipts shrink 60–75%, vector slide decks barely move.
How to compress PDF in 4 steps
- 1
Upload your PDF
Drag the file onto the box above, or click to browse. The tool accepts a single PDF up to 100 MB.
- 2
Pick a compression level
Light keeps the file near-original (5–15% smaller). Standard hits the sweet spot for most use cases (30–55% smaller). Strong is for emergencies where size matters more than detail (60–75% smaller).
- 3
Click Compress PDF
The browser does the re-encoding locally. A typical 30-page mixed PDF takes 1–3 seconds on a 2020-era laptop.
- 4
Compare and download
The file info panel shows original vs compressed bytes side by side. If the result is too aggressive, run again at a lighter level — your original is still on disk.
Compression level vs file size: what to expect
How much you can shrink a PDF depends almost entirely on what's inside. We compressed five common source types at each level. The numbers below are real, measured in October 2025.
| Source type | Original | Light (95% Q) | Standard (75% Q) | Strong (55% Q) |
|---|---|---|---|---|
| Text-only contract (10 pages) | 380 KB | 372 KB (−2%) | 340 KB (−10%) | 320 KB (−16%) |
| Mixed report w/ images (30 pages) | 8.4 MB | 7.1 MB (−15%) | 4.6 MB (−45%) | 2.9 MB (−65%) |
| Scanned receipts (40 pages) | 22 MB | 18 MB (−18%) | 9.8 MB (−55%) | 5.4 MB (−75%) |
| Photo-heavy portfolio (15 pages) | 45 MB | 39 MB (−13%) | 22 MB (−51%) | 11 MB (−76%) |
| Vector slide deck (20 pages) | 1.2 MB | 1.18 MB (−2%) | 1.15 MB (−4%) | 1.1 MB (−8%) |
Why scanned PDFs shrink the most
A scanned page is a JPEG of paper, often saved at 300 DPI. The file carries far more pixel detail than the human eye uses on screen. Standard compression drops the image quality from ~95 to ~75, which is invisible at normal zoom but cuts the bytes by half.
Why vector PDFs barely shrink
Vector content — slide decks exported from Keynote, charts from R, PDFs generated by LaTeX — uses math curves, not pixels. There are no images to recompress. Light, Standard, and Strong all converge on a 5–10% saving from font subsetting and metadata cleanup.
Pick the right level for your scenario
If you don't want to think about it, pick Standard. It hits the right balance for the vast majority of PDFs. The table below covers the cases where Standard isn't the answer.
| Your goal | Recommended level | Expected output | Notes |
|---|---|---|---|
| Email attachment under 25 MB | Standard | 30–55% smaller | Gmail and Outlook safe |
| Sub-10 MB email squeeze | Strong | 60–75% smaller | Visible quality drop on photos |
| Web download or portal upload | Standard | 30–50% smaller | Best for users on mobile data |
| Long-term archive | Light | 5–15% smaller | Preserves fidelity for the future |
| Print submission (300 DPI) | Light | 5–15% smaller | Standard / Strong will print fuzzy |
| Sharing on slow mobile data | Strong | 60–75% smaller | Smallest possible at readable quality |
If two of these apply at once — say, a print submission you also need to email — pick the higher quality level (Light) and split the file into two halves first instead of compressing harder.
Compress vs split vs merge: which tool fixes a too-big PDF?
Compression is the right answer for most oversized PDFs, but not all. The matrix below covers the common cases.
| Situation | Compress PDF | Split PDF | Merge first |
|---|---|---|---|
| One huge PDF over the email cap | partial | ||
| Several files together too big | |||
| Want only some pages of a long PDF | |||
| File is image-heavy and oversized | |||
| Already vector-only, still huge | |||
| Scanned at 600 DPI by mistake |
Pattern: compress PDF when image bytes are the problem. Split when the file is genuinely too long. Merge first only when the oversize comes from having many separate files that you'll want to email as one.
Common compress PDF problems and how to fix them
My PDF won't compress further
If Strong only saves 5–8%, the source is probably vector content (slide decks, LaTeX, generated reports). There are no images to re-encode. Splitting the PDF into smaller files is the next move — our PDF split tool handles that in seconds.
The compressed PDF looks fuzzy on screen
Strong drops images to JPEG quality 55, which shows on photos and detailed scans. Re-run at Standard (quality 75) or Light (quality 95). Light is visually lossless for almost every viewing situation.
Compress fails on a 200+ MB file
Browser memory caps out somewhere between 150 and 300 MB depending on your device. Split the PDF into halves first, compress each half, then merge the results. Mobile browsers hit this wall earlier — laptop is more reliable for very large files.
Compressed PDF is still over the email cap
Gmail's 25 MB and Outlook's 20 MB are unforgiving. If Strong + Standard both leave you over the cap, split the file into two parts and send separately. For receipts and scans, also try re-scanning at 200 DPI rather than 600 DPI — that fixes it at source.
5 pro tips for better compression
Match level to source type
Text-heavy → Light. Mixed reports → Standard. Scanned receipts and photo PDFs → Standard or Strong. Vector slide decks → don't bother.
Compress AFTER merging
If you're combining several PDFs, merge first, then run compress PDF on the result. One pass at the end is faster and shrinks better than compressing each input.
Re-scan at 200 DPI
If you control the scan, set the scanner to 200 DPI before saving. The file is smaller from the start, and Standard compression takes you the rest of the way.
Standard first, always
Start at Standard. If the result is still too big, escalate to Strong. Skip Light unless you need archive-grade fidelity.
Keep your originals
Compression is one-way. The lost image data cannot be recovered from the compressed file. Archive the original somewhere before you replace it.
Complete PDF Tool Suite
Discover our comprehensive collection of PDF tools designed to handle all your document needs
PNG to PDF
Bind PNG images into a single, print-ready PDF
JPG to PDF
Convert JPG images to PDF format
Merge PDF
Combine multiple PDF files into one
Compress PDF
Reduce PDF file size efficiently
PDF to PNG
Convert PDF pages to PNG images
PDF to Text
Extract text content from PDF files
Split PDF
Split PDF into separate pages
Edit PDF
Edit and annotate PDF documents
Organize PDF
Organize and rearrange PDF pages
Frequently asked questions
Common questions about compressing PDF files
Is PDF compression free?
Yes — every compression on this page is free with no sign-up. No daily cap, no watermark, no upsell to a paid tier.
How much can I shrink a PDF?
Between 5% and 76% depending on the source. Scanned and image-heavy PDFs lose the most weight; vector slide decks barely change.
Does compressing reduce quality?
Light is visually lossless; Standard and Strong re-encode images at lower quality. Standard is invisible at normal zoom for most documents. Strong shows artifacts on photos but is fine for text scans.
What's the difference between Light, Standard, and Strong?
They map to JPEG quality 95, 75, and 55 for embedded images. Light cuts 5–15%, Standard cuts 30–55%, Strong cuts 60–75%. Text and vector content are not re-encoded at any level.
Will compress PDF work on scanned documents?
Yes — scanned receipts and forms are where compression delivers the biggest savings. Standard typically halves the file size; Strong takes off two-thirds.
Can I compress PDF without losing image quality?
Pick Light — it keeps images at JPEG quality 95. Visually lossless for almost every viewing situation, with a modest 5–15% size reduction.
Why won't my PDF compress further?
Vector PDFs (slide decks, LaTeX exports) hit a 5–10% floor. There are no raster images to re-encode. If you need a smaller file, split the PDF instead.
Is it safe to upload PDFs to compress online?
This tool doesn't upload anything. Compression runs entirely in your browser using JavaScript. The PDF stays on your device and is released from memory when you close the tab.
Can I compress PDF on iPhone or Android?
Yes, this page runs in mobile Safari and Chrome. Phone browsers have less RAM, so files over ~50 MB may compress slowly or fail; try splitting first if you hit that wall.
How do I compress a PDF for email?
Pick Standard — it gets most files under 25 MB. If your source PDF is over 50 MB, run Strong; if it's still over the cap, split into two halves and send separately.
Related PDF tools
If you came here to compress PDF files, you'll probably need one of these next:
- Merge PDFs into one before compressing — one compression pass at the end is faster than several.
- Split a huge PDF into smaller parts — the right answer when compression hits a floor.
- Convert JPG to PDF first — if your source is photos, control quality at conversion.
- Extract text instead of compressing — for searchable archives where size matters more than layout.
- How our tools work — privacy and architecture overview.
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