Compress PDF

Choose Smallest size, Balanced, or Best quality and download a smaller PDF in seconds — no fixed file-size target required.

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By Muhammad Abdullah Rauf · Founder, EverydayTools.proUpdated 2026-05-17

What is a PDF compressor?

A PDF compressor reduces file size in your browser using pdf-lib and PDF.js — metadata cleanup, optional lossless optimization, and JPEG raster passes for image-heavy pages — without uploading your file to any server.

PDF files grow large primarily because of embedded images — scanned documents and photo-heavy PDFs can easily reach 10–50 MB. This compressor runs locally and offers three presets: **Smallest size** (maximum reduction), **Balanced** (recommended for most files), and **Best quality** (lightest compression, highest visual fidelity).

With **Keep text searchable** enabled, pdf-lib optimizes structure and metadata without rasterizing text-heavy pages when possible. With it off — or on scan-heavy pages — PDF.js renders pages to canvas, encodes JPEG at the preset quality, and pdf-lib rebuilds the PDF. Text-only PDFs may shrink only 5–15% because PDF text is already compact.

Quick answers

Concise answers for common searches — definitions, steps, and comparisons.

What causes a PDF to have a large file size?

Embedded high-resolution images are the primary cause — a single full-page scan at 300 DPI can exceed 1 MB on its own. Other contributors include uncompressed or losslessly-compressed raster images, embedded font programs (every typeface used gets included in the file), duplicate resource streams (the same image or font stored multiple times across pages), and raw pixel data from design apps that export without web optimization. Metadata overhead, ICC colour profiles, and print-production artifacts add kilobytes but rarely megabytes. Scanned documents are the worst case: every page is a full-resolution image with no vector or text layer to defer to.

What is the difference between a text-based PDF and a scanned PDF?

A text-based PDF stores actual text characters, fonts, and vector paths as compact object streams. The file describes what to draw rather than storing pixel data, so a 50-page text document may be only 200–500 KB. A scanned PDF is a sequence of raster images — photographs of paper pages — stored as JPEG or uncompressed bitmaps. Each page is a picture, not text, so file size scales directly with page count, scan resolution, and colour depth. This distinction determines compression behavior: text-based PDFs compress 5–15% with structure optimization, while scanned PDFs compress 50–80% by re-encoding the embedded images at a lower JPEG quality. Searchability is also different — text PDFs support copy-paste and Ctrl+F natively; scanned PDFs require OCR to make text selectable.

At what point does PDF compression visibly degrade quality?

Visible degradation depends on content type and the preset chosen. Scanned text documents: JPEG quality below ~50% introduces ringing artifacts around letter edges and blotchy backgrounds — readable on screen but unprofessional when printed or inspected at 150%+ zoom. Photographs and diagrams: quality loss is visible below ~40% JPEG quality as blockiness in gradients and fine detail. Text-and-graphics PDFs: compression artifacts are most obvious on thin lines, fine serif fonts, and high-contrast edges. The Balanced preset (~60% JPEG quality) is chosen to stay above these thresholds for most documents. Smallest size (~30% quality) should only be used when file size matters more than visual fidelity — for example, a portal upload that no one will print.

How to use Compress PDF

  1. Upload your PDF

    Drag and drop or click to browse (up to 50 MB). The file stays in your browser — nothing is uploaded to our servers.

  2. Choose a preset

    Pick Smallest size for maximum reduction, Balanced for everyday use (recommended), or Best quality when you need the least visual loss. Toggle Keep text searchable for forms and text PDFs; turn it off for stronger shrink on scans.

  3. Compress and review

    Click Compress PDF. The tool shows before/after size and percent saved when the output is smaller.

  4. Download or adjust

    Download the compressed PDF. If still too large for a portal cap, try Smallest size, turn off searchable mode for scans, split the file, or use Compress PDF to 1MB for an automatic under-1-MB target.

Who uses Compress PDF?

Common real-world scenarios where this tool saves time.

Email attachments under size limits

Shrink PDFs for Gmail (25 MB), Outlook (20 MB), or stricter corporate limits. Start with Balanced; use Smallest size if the file is still too large.

Portal and form uploads

Reduce scan-heavy PDFs before HR, legal, or government portals. For a strict 1 MB cap, use Compress PDF to 1MB after trying Smallest size here.

Cloud storage optimisation

Archive smaller copies of large PDF folders without uploading files to a third-party compressor.

Faster web sharing

Compress before sharing Drive or Dropbox links so mobile recipients download faster.

Scanned document workflows

Turn multi-page scanner output into email-safe PDFs — turn off Keep text searchable when you do not need selectable text on scans.

Workflow guides

Step-by-step chains that connect related tools for common tasks.

Email attachment: compress → verify → send

  1. Upload the PDF and start with Balanced preset; use Smallest size if still over your mailbox limit.
  2. Preview signatures and fine print at 100% zoom before upload.

Compress PDF examples

Scanned 20-page report — Balanced preset

Input

8.5 MB scanned report (all images) · Preset: Balanced · Searchable text: off

Output

2.1 MB compressed · ~75% reduction

Scanned PDFs are full-page images. Balanced JPEG encoding at moderate render scale shrinks the file dramatically while keeping on-screen text readable.

Marketing brochure — Smallest size for email

Input

12 MB brochure (photos + text) · Preset: Smallest size

Output

3.4 MB compressed · ~72% reduction

Photo-heavy pages compress aggressively under Smallest size. Fine print may soften at high zoom; use Best quality if the file will be printed.

Text-only contract — searchable mode

Input

1.2 MB contract (text, no images) · Keep text searchable: on

Output

1.1 MB compressed · ~8% reduction

Lossless metadata optimization only — little image data to re-encode. For large text-only PDFs, font subsetting in the source app helps more than raster compression.

How PDF compression works in your browser

Processing runs entirely on your device. (1) **Keep text searchable on** — pdf-lib re-saves with object streams and strips redundant metadata; text-heavy pages may be copied unchanged when the page has enough text items. (2) **Raster mode** (searchable off, or when a page cannot be copied) — PDF.js renders each page to a canvas; JPEG quality follows the preset (Smallest size ~30%, Balanced ~60%, Best quality ~80% at the tool’s render scale). (3) pdf-lib assembles the output PDF. Reduction % shown is the exact byte difference between upload and download.

Limitations

  • Maximum 50 MB per file — very large or page-heavy PDFs may take longer and use more memory in the browser.
  • Text-only PDFs often shrink only 5–15%; re-export from the source app with optimize-for-web settings when needed.
  • Smallest size on scanned pages can soften fine text — preview before submitting official forms.
  • Password-protected PDFs must be unlocked before compression.

Sources

Reference tables

PDF compression tools compared (2026)

Free tools for reducing PDF file size.

ToolPrivacyBrowser-basedCompression levelsWatermarkSignup
EverydayToolsLocal only — no uploadYesSmallest / Balanced / Best qualityNoneNo
SmallPDFServer uploadYesOne levelNone (free)Optional
ILovePDFServer uploadYesOne levelNone (free)Optional
Adobe Acrobat (web)Adobe cloud uploadYesMultiple presetsNoneRequired
PDF24 ToolsServer upload (EU)YesMultiple presetsNoneNo

Expected compression by PDF content type

Typical size reduction with the Balanced preset (searchable off on scans).

PDF TypeContentExpected ReductionNotes
Scanned document100% raster images50–80%Best compression candidate
Mixed (text + photos)Text + embedded photos30–60%Depends on photo count and quality
Presentation/slidesText + diagrams + photos20–50%Photo slides compress well; diagram slides less so
Text-onlyNo embedded images5–15%Minimal gains — re-export from source instead
Vector-heavy brochureMostly vector + some photos10–30%Only photo elements compress significantly
Strict 1 MB portal capAny content typeVariesUse /compress-pdf-to-1mb for automatic target sizing

PDF compression: what gets compressed?

Which PDF content types shrink with raster compression and which stay intact.

Content TypeCompression AppliedQuality Impact
Embedded JPEG/PNG in raster modeRe-encoded as JPEG at preset qualitySlight to moderate detail loss depending on preset
Text-heavy pages (searchable on)Often copied or optimized losslesslyText and vectors stay sharp when not rasterized
Vector graphicsUnchanged when page is copiedNo change when vectors are preserved
Bookmarks / hyperlinksPreserved in structureNo change
Metadata (author, title)Stripped or reduced in optimization passNo visible change

Best results on scans and photo-heavy exports. Mostly text? Keep text searchable on and expect modest byte savings.

When to use Compress PDF vs related tools

Related toolUse this tool whenUse related tool when
Compress PDF to 1MBYou want to pick Smallest size, Balanced, or Best quality yourself and accept whatever file size resultsA portal requires a strict maximum (e.g. under 1 MB) and you want the tool to iterate quality until the cap is met
Merge PDFYou need to shrink one existing PDF’s file sizeYou have multiple PDFs to combine — merge first, then compress the merged output
Split PDFYour PDF is within the 50 MB size limitYou want to extract or work with specific page ranges before compressing
PDF to ImageYou need a smaller PDF file that still opens as a PDFYou need standalone PNG/JPEG pages, not a PDF

Best practices

Start with Balanced

Balanced is the recommended preset for most PDFs — good size reduction without the aggressive loss of Smallest size.

Compress after merging

Merge multiple PDFs first, then compress once on the combined file to avoid compounding quality loss.

Use Compress PDF to 1MB for strict caps

Government and job portals often require an exact maximum (e.g. 1 MB). Target-size compression automates quality steps.

Keep originals for archiving

Store uncompressed sources; share compressed copies for email and uploads.

Preview on mobile before sending

Smallest size can look acceptable on desktop but softer on high-DPI phones — check legibility before client delivery.

Common mistakes to avoid

Using Smallest size for a document you will print

Smallest size uses aggressive JPEG encoding — artefacts show in print. Use Best quality or Balanced for anything that will be printed or archived at high fidelity.

Compressing an already-compressed PDF

Re-compressing adds quality loss with little extra savings. Compress from the original source file when possible.

Expecting large reductions from text-heavy PDFs

Keep text searchable on for lossless optimization only. For text-only files over a few MB, enable font subsetting in Word or your design app.

Deleting the original after compressing

Raster compression is lossy. Keep the uncompressed original for print, legal, or re-editing.

Troubleshooting

PDF will not load — password or corruption

Fix:

Output is almost the same size as the original

Fix:

Scanned text looks blurry

Fix:

Compression is slow or the tab freezes

Fix:

Frequently Asked Questions

Does compressing PDFs upload my files to a server?

No. Compression runs in your browser with pdf-lib and PDF.js. Your PDF never leaves your device.

What are Smallest size, Balanced, and Best quality?

Smallest size applies the strongest JPEG compression and lower render scale for maximum byte reduction. Balanced is recommended for everyday use. Best quality keeps higher JPEG quality and scale for the least visual loss.

How much will my PDF shrink?

Scanned PDFs often shrink 50–80% on Balanced with searchable mode off. Mixed text and photos: 30–60%. Text-only with searchable on: often 5–15%.

Will compression affect selectable text?

With Keep text searchable on, text-heavy pages are usually preserved as vectors. With it off, pages may be rasterized to JPEG and lose selectable text — best for scans when you do not need search.

Can I compress a password-protected PDF?

Only after you remove the password and save an unlocked copy. Encrypted files cannot be processed in the browser.

What preset should I use for email?

Start with Balanced. If the attachment is still too large, try Smallest size or split the PDF. For a fixed 1 MB portal limit, use Compress PDF to 1MB.

What file size limit applies?

Up to 50 MB per file so compression stays stable in your browser. There is no fixed page count limit, but very long PDFs may take longer to process.

Why did my file get larger after compression?

Some text-only PDFs are already optimized — re-saving adds overhead. The tool reports this and names the download “-processed” when size increases.

How is this different from Compress PDF to 1MB?

This tool lets you choose a quality preset without a fixed output size. Compress PDF to 1MB automatically lowers quality until the file is under 1 MB (1,048,576 bytes).

Privacy, accuracy, and trust

Privacy

All compression runs locally in your browser using pdf-lib and PDF.js. Your PDF is not uploaded to EverydayTools servers — it stays in device memory until you download the result.

Accuracy

The before/after sizes and reduction percentage reflect the actual byte length of your upload versus the generated PDF. If the output is larger than the input, the UI states that explicitly.

Part of PDF Tools

Related Tools

More free tools for the same workflow.

Compress PDF to 1MB

Automatically compress any PDF to under 1MB without manually tuning quality settings. Built for government portals, job applications, and upload forms with a hard 1MB file-size cap. Browser-based — your file stays on your device.

Flatten PDF

Free PDF flattener — merge form fields, annotations, and layers into a flat, non-editable PDF. Ideal for submitting completed forms and archiving final documents. No signup.

PDF to Grayscale

Free PDF grayscale converter — turn any color PDF into black and white for printing, file size reduction, and archiving. Fully browser-based, no upload to server. No signup.

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Reviewed by EverydayTools Editorial Team on 2026-05-17.