Are you trying to email a PDF, but the attachment turns out to be too large? This is a common problem with scanned documents, reports with many images, presentations, invoices, and other files containing high-resolution images.
Compressing a PDF reduces the file size, making it easier to attach, upload, save, and share. Depending on the document, you can make the file significantly smaller while the text and images remain readable.
In this guide, you will learn how to compress a PDF for email, gain insight into email attachment limits, and resolve issues with files that are still too large to send.
How do you compress a PDF online for email?
Using an online PDF compression tool is one of the simplest ways to reduce a document’s file size without installing additional software.
Step 1: Open the PDF compressor
Go to FileNivo PDF Compressor to get started. Step 2: Upload your PDF
Select the PDF document you want to compress from your computer or device. If the document contains confidential information, check the tool’s privacy policy before uploading it.
Step 3: Compress the file
Follow the on-screen instructions on the tool to start the compression. If compression levels are available, choose an appropriate setting based on the document’s content and desired file size.
A document consisting primarily of text may react differently than a PDF containing many high-resolution photos or scanned pages.
Step 4: Download the compressed PDF
Once compression is complete, download the resulting file to your device.
Step 5: Check the file before sending it by email
Open the compressed PDF and review a few pages. Ensure that the text is readable, diagrams are clear, and that important details have not been lost.
Also check the new file size. If it is still too large for your email provider’s attachment limit, try a different compression setting or use one of the alternatives below.
Tip: Keep a copy of the original PDF until you have confirmed that the compressed version is suitable for sharing.
Why should you compress a PDF before sending it by email?
PDF files can become large for various reasons. Common examples include:
High-resolution photos embedded in the document.
Scanned pages saved as large images. Graphic elements and illustrations containing a lot of image data.
Embedded fonts and other document sources.
Large reports with many pages and visual elements.
A PDF file containing only text is often already relatively small, meaning compression results in only a modest reduction. A scanned document or a brochure with many images may offer more opportunities to reduce file size.
Compressing a PDF can facilitate attaching documents, shorten upload times, and make files easier to share with colleagues, clients, teachers, or contractors.
What is the maximum size of email attachments?
Email providers apply limits to the total size of messages and attachments. These limits vary by provider and account type.
For example, Gmail generally allows attachments up to 25 MB per message. If the total size of the attachment exceeds this limit, Gmail may use Google Drive to share the files.
Other email services may apply different limits, and some work or school accounts have additional restrictions. The relevant limit is the one imposed by your email provider and the recipient’s system.
It is also important to know that the total size of an email can be larger than the original attachment, due to the way attachments are encoded for transmission.
Before compressing a PDF, check your email service’s attachment limit. If your document is only slightly too large, compression may be sufficient. If it is much larger, you may need to compress it more strongly, split the document, or share it via a link to cloud storage.
How small should a PDF be for email?
There is no ideal PDF size for every email. Your target file must stay well below the attachment limit so that there is room left for other files and message overhead.
Here are some examples to illustrate:
| Original PDF size | Compressed size | Size reduction |
|---|---|---|
| 10 MB | 6 MB | 40% |
| 20 MB | 12 MB | 40% |
| 30 MB | 18 MB | 40% |
These figures illustrate how the size reduction is calculated; they are not a guarantee of compression results. The actual result depends on the document, the images, the original PDF settings, and the compression method.
If a PDF is already optimized, the reduction may be slight. If the document contains large scanned images, compression may have a greater effect.
5 ways to make a PDF smaller for email
If your PDF is still too large after compression, try these methods.
Compress embedded images
Images often make up a large part of a PDF’s file size, especially when the document contains scanned pages or photos.
Image compression reduces the amount of data stored for those images. Some methods preserve image information, while others reduce file size by removing data that might not be noticeable in standard display formats.
For documents containing primarily photos, image compression can make a significant difference. Be extra careful with contracts, receipts, and forms, as small text, signatures, and details must remain legible.
Reduce image resolution where necessary
A PDF may contain images with a much higher resolution than is necessary for display on a screen.
If the document is intended only for email and standard screen display, reducing unnecessary image resolution can help reduce file size.
However, do not simply reduce the resolution. Documents intended for professional printing, detailed technical review, or long-term archiving may require higher-quality images.
Always check the compressed document for a readable zoom level before sending it.
Remove unnecessary content
If the document contains pages or content that the recipient does not need, create a smaller copy containing only the relevant material.
For example, you can remove duplicate pages, unused attachments, or irrelevant supporting material.
Ensure that you retain all information the recipient needs. If the original is an official, signed, or legally important document, do not remove any content that must remain intact.
Split a large PDF file into smaller files
Sometimes a document is too large to send as a single attachment, even after compression.
Splitting it into smaller, clearly labeled files can help. For example, a long report can be divided into separate sections or chapters.
Keep the pages in the correct order and give the files clear names, such as Report-Part-1.pdf and Report-Part-2.pdf.
Splitting does not necessarily reduce the total amount of data, but it can help you stay within the limits per attachment. Check if your email provider also applies a limit on the total message size.
Share the PDF via a link to a cloud storage service
If the file remains too large, sharing a link might be more convenient than sending the PDF directly as an attachment.
You can upload the document to a cloud storage service and send the recipient a link with the appropriate access rights.
Before sharing the file, check whether the recipient can open it. Avoid public access if the document contains sensitive or private information, and use restricted sharing rights where necessary.
This approach is particularly useful for large reports, portfolios, manuals, and collections of documents.
Does compressing a PDF reduce quality?
It can, but the degree of quality loss depends on the compression method and the content of the document.
Some compression techniques reduce redundant data without altering the visible content of the document. Other techniques reduce the quality or resolution of embedded images to obtain a smaller file.
The difference is important:
Text-based PDFs: Text can often remain sharp if the document is compressed correctly.
Scanned PDFs: Each page can be stored as an image, so image compression can affect text clarity.
PDFs with many photos: Reducing image data can yield significant savings, but excessive compression can cause visible artifacts.
Forms and signed documents: Carefully check text, signatures, checkboxes, and other important details after compression.
The goal is not just to create the smallest possible PDF. The goal is to create a file that meets your email requirements without compromising the information the recipient needs.
Common problems when compressing a PDF for email
The PDF is still too large
The original document may already be compressed or contain many high-resolution images.
Try a different compression level if available. You can also remove unnecessary content, split the document, or share it via a cloud link.
The compressed PDF looks blurry
The compression settings may have reduced the quality of embedded images too much.
Use a less aggressive setting or start over with the original PDF. If the document contains small text or detailed scans, prioritize readability over maximum file size reduction.
The PDF cannot be opened after compression
The file may not have been fully downloaded or the compression process failed.
Try downloading the file again and opening it in a trusted PDF reader. If the problem persists, use the original document and repeat the compression process.
The email is rejected, even though the PDF is small enough
Your email provider may calculate the total message size, including attachment encoding and other attachments. The recipient’s email service may also apply a smaller limit.
Try further reducing the total attachment size or share the PDF via a link to a cloud storage service.
The PDF contains sensitive information
Do not upload confidential documents to an online tool unless you are familiar with how it handles data. Consult the provider’s privacy policy and file retention policy. For highly sensitive files, consider an approved offline application.
Frequently Asked Questions
How do I compress a PDF for email for free?
You can use an online PDF compression tool, such as FileNivo PDF Compressor. Upload the document, follow the compression instructions, download the result, and check that the file is small enough and remains moderate. Check the current features and limitations of the tool before using it.
How do I reduce a PDF from 20 MB to 5 MB?
A reduction from 20 MB to 5 MB requires a 75% decrease in file size. Whether this is possible without acceptable loss of quality depends on the document. Try compression first, especially if the file contains high-resolution images. If the result is not small enough, you can consider lowering the resolution of the images, removing unnecessary pages, or splitting the PDF.
Do you want to change the content of a PDF while compressing it?
Compression can reduce the file size without potentially changing the content, but some methods may remove image quality or delete certain types of data. Always check the result and keep the original file if you need an unaltered copy.
Can I compress a scanned PDF file?
Yes. Scanned PDFs contain page images, which often offers opportunities to structure the file size. However, strong compression can cause small text, stamps, signatures, and small print to become difficult to read. Check the result carefully before sharing it.
Is a compressed PDF file still searchable?
That depends on the original document and the compression process. A PDF containing actual text generally remains searchable if that text has been preserved. A scanned PDF file may require optical character recognition (OCR) to make the text searchable. Compression alone does not provide OCR functionality.
Can I compress a PDF on my phone?
You can use a compatible online PDF compressor in your phone’s browser, provided the tool supports your file size and device. After compressing, open the downloaded document and check if it is readable before attaching it to an email.
What should I do if my PDF exceeds the email attachment limit?
Try compressing the PDF, removing unnecessary content, or splitting the document into smaller files. If the document is still too large, upload it to a cloud storage service and send a link with the appropriate access rights.
Does compressing a PDF make emailing safer?
No. Compression primarily reduces file size; it does not automatically encrypt the document or protect its content. If you need to send confidential information, use an appropriate data sharing method and follow your organization’s data processing guidelines.
In conclusion
Compressing a PDF can make sending and receiving email attachments easier, especially when the document contains large images or scanned pages. Start with a suitable compression setting, check the readability of the result, and ensure that the final file fits within your email provider’s attachment limit.
If compression alone is not sufficient, you can consider reducing the resolution of unnecessary images, splitting the document, or sharing it via a link to a cloud storage service.
Ready to reduce your document’s file size? Try the FileNivo PDF Compressor and get your PDF ready for easier sharing.