PDF Compressor

Bring a PDF under an upload limit by downsampling what sits inside it.

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Up to 50 MB per file. Sign up free to compress files up to 100 MB.

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How to compress PDF files online

PDF compression works differently from image compression. Most of the file size comes from the images embedded in it, and those are what our tool shrinks.

1

Upload PDF documents

Select your PDF files: scanned documents, reports, presentations, or ebooks. Encrypted and password-protected PDFs are not supported.
2

Set a target size

Enter the size you need, such as 500 KB for an email attachment or the limit a portal states. The compressor lowers embedded image resolution until the file fits, and stops at the highest quality that does.
3

Download compressed PDFs

Text stays text, and searchable, while downsampling is enough to reach your target. Ask for a size it cannot reach and the pages are rendered to images instead, which makes the size but ends the text layer.

What this compressor does well

Image Downsampling

Embedded images often account for 90%+ of PDF size. Downsampling high-res photos from 300 DPI to 150 DPI halves pixel count while staying sharp on screen.

Font Subsetting

A full font file can be 500 KB+. Subsetting keeps only the glyphs actually used in the document, often reducing font data to under 30 KB without affecting rendering.

Metadata Removal

PDFs carry hidden data: edit history, thumbnail previews, XML metadata, and duplicate objects. Stripping these can recover 5-15% of file size with no visible change.

Pages Rendered Only as a Last Resort

When a target is too small for downsampling, every page is rendered to an image so the file still fits. Pick a larger target if you need to search or copy the text.

Email-Ready Compression

Most email providers cap attachments at 25 MB. Set a target under that and the embedded images shrink while the text stays text.

Scanned Document Support

Scanned PDFs are essentially large images. Compression can reduce a 20 MB scan to under 2 MB by downsampling to 150 DPI and applying JPEG compression to embedded images.

A target size, not low, recommended or extreme

Most PDF compressors ask you to pick a vague quality level, "low", "recommended", "extreme", then hand back whatever size that happens to produce. If you are trying to clear a specific limit, that means uploading, checking the result, and trying again. This tool works the other way round: you name the size you need and it compresses to fit, so one pass is enough.

Upload limits worth knowing

The caps people most often run into, and what each one really means in practice.

Where	Limit	In practice
Gmail	25 MB	Attachments above this are converted to a Drive link instead of sending.
Outlook.com	20 MB	Outlook desktop against Exchange is often capped lower, at 10 MB.
Slack (free plan)	1 GB total	Per-file uploads are fine; the workspace storage cap is what runs out.
Microsoft Teams	250 MB	Generous per file, but channel storage draws on the SharePoint quota.
LinkedIn documents	100 MB	Up to 300 pages; large files are slow to render on mobile.
WordPress (default)	2 MB	Set by PHP's upload_max_filesize; many hosts leave the default in place.

Email attachments are Base64-encoded in transit, which inflates them by roughly 33%. A 20 MB file arrives as about 27 MB, so a 25 MB cap is really closer to 18 MB of actual payload. Leave headroom rather than compressing to exactly the published limit.

How PDF compression works

PDFs are containers. The file size comes from three sources: embedded images (usually 70-95% of total), embedded fonts (5-10%), and vector page content (rest). Compressing to a smaller target attacks the images first: recompressing each embedded image with JPEG at lower quality, then downsampling from 300 DPI (print quality) to 150 DPI (screen quality) or 96 DPI (mobile quality). A scanned 100-page PDF at 20 MB can hit 2 MB via this route without touching page count or layout. Text-only PDFs are already near their floor and rarely compress by more than 15-20%.

Which target size to pick for PDF

Different portals cap PDF uploads at different sizes. Pick the target that matches where you’re uploading rather than shrinking blindly, over-compressing wastes visible quality, under-compressing gets rejected.

50KB

Text-only documents and signature scans

50 KB only leaves room for pages that are mostly text.

100KB

Scanned pages at reading resolution

100 KB is the first target where a full scanned page stays comfortably readable.

150KB

When a hard upload cap is the reason

Measured: a 13.2 MB three-page 300 DPI scan lands at 96 KB and an 8.9 MB photo-heavy PDF at 82 KB, both well inside 150 KB.

200KB

The best quality that still clears a 200 KB cap

200 KB is the first PDF target where photo-heavy files keep real detail.

500KB

ITR supporting documents & bank statements

Income Tax Return supporting document uploads (Form 16, salary slips, rent receipts) and 3-month bank statement PDFs for loan applications typically cap at 500 KB per file.

1MB

Email attachments and document archives

1 MB sits inside every common attachment limit while costing almost no visible quality.

2MB

GST registration & RTI application bundles

GST registration (REG-01) authorised-signatory document bundles and RTI online application attachments accept PDFs up to 2 MB.

Frequently asked questions

How do I compress PDF files online?

Choose a target size, upload your PDF file, and click Compress. iFormat shrinks it to your chosen size while keeping quality as high as possible, free, no watermark, and no account needed.

What sizes can I compress PDF to?

Dedicated pages cover 50KB, 100KB, 150KB, 200KB, 500KB, 1MB or 2MB. Pick the size that matches the upload limit or email cap you need to meet.

How does PDF compression work?

PDF compression targets embedded images, the largest component of most PDFs. The compressor downsamples high-resolution images (often 300+ DPI) to screen-appropriate resolution and re-encodes them with more efficient compression. Text, fonts, and vector graphics stay crisp and selectable while that is enough; a target it cannot reach renders the pages to images, which ends the text layer.

Will compressing reduce PDF quality?

Text stays sharp and selectable at most targets, with only the embedded images affected. At a target that cannot be reached any other way, the pages are rendered to images and the text stops being selectable. For scanned documents (image-only PDFs), compression reduces the scan resolution. A 300 DPI scan compressed to 150 DPI is still readable on screen but may lose fine print detail when zoomed or printed.

Is the PDF compressor free?

Yes. Compressing PDF files is free with no watermark and no sign-up. Paid plans only raise file-size and batch limits.

Are my PDF files kept private?

Yes. Uploads use an encrypted HTTPS connection, compression runs on an isolated worker, and both your original and the compressed file are deleted automatically within 1 hour, and nothing is stored, shared, or used for training.

Will compressing a PDF break fillable form fields?

Not while downsampling the embedded images is enough to reach your target: the PDF structure, form fields and checkboxes stay as they are. A target it cannot reach renders the pages to images, which flattens the form, so pick a larger target for a form you still need to fill in.

Can I compress a password-protected PDF?

If the PDF has an owner password (restricting editing/printing) but allows viewing, the compressor can process it. If the PDF requires a password to open (user password), you'll need to remove the password first.