Secure your PDF with strong password protection and encryption.
Reduce file size without losing quality.
Outlook has a strict 20 MB attachment limit (or lower for corporate accounts). If your PDF exceeds this limit, your email will fail to send. Our free online tool compresses your PDF to under 20 MB while keeping text and images clear. No sign-up, no software – just upload, compress, and send your email.
Did you know? Outlook.com limits attachments to 20 MB. Corporate Exchange accounts often have 10‑20 MB limits, with some going up to 35 MB. Many PDFs – especially those with images, scans, or complex formatting – exceed these limits. Our compression brings your PDF under the limit in seconds, so you can send your email without any hassle.
Outlook is one of the most widely used email clients, both for personal and business use. However, one of the most common frustrations for users is the attachment size limit. When you try to send a PDF that exceeds Outlook's limit, the attachment is blocked and your email cannot be sent.
Here are the key reasons why large PDFs cause Outlook sending failures and how our compression tool solves them:
Outlook.com enforces a 20 MB limit. If your PDF exceeds this, you will receive an error and the email will not send.
Exchange administrators often set lower limits – typically 10‑20 MB – to protect server resources. Exceeding these limits causes immediate rejection.
PDFs containing high‑resolution photos, scanned documents, or embedded images often exceed 20 MB quickly.
Unlike some email providers, Outlook does not allow users to increase the attachment limit – it is set by Microsoft or your IT department. Compression is the only practical solution.
Outlook limits vary depending on the account type and organisation. Here is a quick reference:
Compression is the safest way to ensure your PDF attaches to Outlook successfully, regardless of your account type or organisation.
Our tool uses a combination of smart techniques to reduce file size while preserving the integrity of your document. Here is what happens when you compress a PDF for Outlook:
The result is an Outlook‑ready PDF that looks identical to the original but fits comfortably under the 20 MB (or lower) limit.
Compression reduces file size while keeping all content intact. Our tool uses smart algorithms to optimise images and data, making your PDF Outlook‑ready.
DonePDF Compress PDF in your browser (Chrome, Safari, Edge, Firefox).
Upload your PDF from device, cloud, or drag & drop.
Choose compression level – “Standard” for high quality, “Maximum” for smallest size.
Click “Compress” – processing takes seconds.
Download the compressed PDF and attach it to your Outlook email with confidence.
Free tier: 3 compressions/day, up to 50 MB. For larger files, paid plans support batch processing and higher limits.
Our tool offers three compression modes tailored to Outlook limits. Here is a quick comparison:
For Outlook, we recommend starting with “High” compression. If your file is much larger (e.g., >30 MB), use “Maximum”.
You might consider these alternatives, but they come with drawbacks:
Our online compressor is free, works everywhere, and preserves PDF quality better than any other method – without depending on IT approvals or cloud storage.
Pro Tip: If your PDF is still over the limit after compression, try converting colour images to grayscale or removing unnecessary pages. You can also use our Split PDF tool to divide the document into smaller chunks and send them as separate attachments in a single email (if Outlook allows multiple attachments totaling under the limit).
Works with Outlook.com, Office 365, Exchange, and all Outlook versions.
Text, images, and formatting remain intact for professional emails.
Process files in seconds with full encryption and auto-deletion.
Use the tool instantly – no sign-up required.
⚡ Need even smaller files for strict corporate Outlook limits?
Our Hyper Compress PDF tool reduces files to the absolute minimum – perfect for 10‑15 MB corporate Exchange limits. Try it for extreme compression.
Outlook.com (personal) has a 20 MB attachment limit. Corporate/Exchange accounts typically have limits between 10‑20 MB, with some organisations setting higher limits (e.g., 35 MB) for Office 365 Enterprise plans. If your PDF exceeds the limit, the attachment will be blocked and your email will fail to send.
Our smart compression preserves text clarity and image quality. You can choose different compression levels – Standard for high quality, Maximum for smallest size. For Outlook, Maximum is often sufficient and text remains sharp and readable.
Absolutely. Our tool preserves fonts, tables, images, and layout. The compressed PDF looks identical to the original – just smaller, making it Outlook‑friendly.
Yes. We use TLS encryption and auto-delete all uploaded files within 2 hours. We never share or store your documents. For extra privacy, use incognito mode.
If your PDF remains above the limit, try "Maximum" compression, use our Hyper Compress tool for extreme reduction, or consider splitting the file into multiple PDFs and sending them in separate emails. You can also use OneDrive to share a link instead of attaching directly – Outlook integrates with OneDrive for large file sharing.
Yes. Scanned PDFs are image‑based and often large. Use our Hyper Compress with grayscale conversion and aggressive JPEG compression to reduce them significantly for Outlook attachments.
Yes, our tool works for all Outlook variants – Outlook.com, Office 365, and Exchange. The output is a standard PDF compatible with all email systems. After compression, you can attach it to any Outlook email without issues.
Upload your PDF and compress it in seconds – free, secure, and ready for any Outlook attachment.
Outlook imposes strict file size limits to ensure fast delivery and prevent network congestion. If your PDF exceeds the allowed size, it will be rejected. Compressing your PDF is the simplest way to meet these requirements.
Large PDFs often contain high‑resolution images, embedded fonts, and unnecessary metadata that increase file size. Our smart compression removes redundant data while preserving document quality, ensuring your PDF meets Outlook limits.
Use "Maximum" compression for image‑heavy documents. For text‑based PDFs, "Standard" or "High" compression preserves clarity while significantly reducing size. Always preview the result before downloading to ensure quality meets your needs.
Explore the full collection of tools in the PDF Size Problems.