Email Attachment Too Large — How to Fix It

You have written the perfect email, attached your files, and clicked send — only to see a red error message: "Attachment too large. Maximum size is 25 MB." Whether it is a PDF portfolio, a batch of high-resolution photos, a video clip, or a ZIP archive, every email user hits this wall eventually. Email attachment size limits exist for a reason (server storage, spam prevention, and delivery reliability), but they are incredibly frustrating when you just need to get a file to someone. In this guide, we break down the exact limits for every major email provider and show you multiple ways to shrink your attachments or send them by other means.

Email Attachment Limits by Provider (2025)

Every email service has a maximum attachment size, and it varies more than you might expect:

• Gmail: 25 MB send limit. You can receive emails up to 50 MB total (including headers and encoding), which means the actual attachment limit is around 34 MB after base64 encoding overhead.
• Outlook.com (Hotmail): 20 MB send limit. Receive limit is 10 MB per attachment, 30 MB total per message.
• Yahoo Mail: 25 MB send limit (both free and paid plans).
• iCloud Mail: 20 MB send limit. Receiving limit depends on Apple's servers but is generally above 20 MB.
• ProtonMail: 25 MB send limit on free accounts (paid plans go up to 100 MB).
• Zoho Mail: 20 MB send limit on free accounts.
• Microsoft Exchange / Office 365 (work email): Typically 20-35 MB, but your IT department can set custom limits. Some organizations allow up to 150 MB internally.

There is an important detail that many people miss: the attachment size limit applies to the encoded message size, not the raw file size. Email protocols use base64 encoding, which inflates binary file sizes by approximately 33%. So a 20 MB PDF actually becomes roughly 27 MB after encoding. This is why your 24 MB file sometimes fails on a "25 MB" limit.

Why Do Email Attachment Limits Exist?

Email was designed in the 1970s to send plain text messages. Attachments were bolted on later through the MIME standard, and the system has always struggled with large files. Here is why providers enforce limits:

• Server storage: Email providers store every message on their servers. A single 50 MB attachment times 1,000 users times 365 days adds up to terabytes of storage.
• Delivery reliability: Large emails are more likely to be rejected by the recipient's server, bounce, or get stuck in transit. Many corporate mail servers reject anything over 10 MB.
• Spam prevention: Spammers and malware distributors often use large attachments to distribute viruses. Size limits help reduce this attack vector.
• Performance: Downloading large emails on mobile devices consumes data and battery life. Limits protect the user experience.

Fix for PDF Attachments

PDF files are the most common oversized email attachment. A scanned document, a design portfolio, or a marketing brochure can easily exceed 25 MB. The solution is PDF compression.

Use our free PDF Compressor to shrink your PDF without significant quality loss. Here is what you can expect:

• Scan-heavy PDFs: 50-70% reduction. A 30 MB scanned document can drop to 9-15 MB while remaining perfectly readable.
• Image-heavy PDFs (brochures, portfolios): 40-60% reduction with minimal visible quality loss.
• Text-only PDFs: These are already small (usually under 1 MB) and rarely need compression.

The process is simple: upload your PDF, choose your compression level (we recommend "High" for email attachments), and download the compressed version. The tool works entirely in your browser — your files stay on your computer.

Fix for Image Attachments

A single photo from a modern smartphone is typically 3-5 MB. Attach ten photos and you are already at 30-50 MB — over most email limits. Here is how to fix this:

Method 1: Compress the Images

Use our free Image Compressor to reduce the file size of each photo. You can batch-compress multiple images at once. At 70% quality, a 5 MB photo shrinks to about 500 KB with barely noticeable quality loss. Ten photos go from 50 MB to 5 MB — well within any email limit.

Method 2: Resize the Images

If your photos are high resolution (4000x3000 pixels or more), you can resize them to a more email-friendly size like 1920x1080 or 1600x1200. This reduces file size by roughly 80% and the images will still look great on any screen. Use our Image Resizer for this.

Method 3: Convert to a More Compact Format

Converting large PNG files to JPEG can dramatically reduce file size. PNG is great for screenshots and graphics with text, but photos should always be JPEG for email. Use our PNG to JPG converter to switch formats.

Fix for Video Attachments

Video files are almost always too large for email. A 30-second 1080p video recorded on an iPhone can be 50-100 MB. A 1-minute 4K video can be 400 MB. You have two options:

Option 1: Compress the Video

Use our free Video Compressor to drastically reduce the file size. Set the output resolution to 720p and the quality to 50-60%. This typically reduces file size by 80-90%, bringing even long videos under email limits.

Option 2: Use a Cloud Link Instead

Video is really not suited for email attachments. Upload the video to Google Drive, Dropbox, or WeTransfer and include a download link in your email instead. This preserves the original quality and bypasses all size limits. We discuss this in detail below.

Fix for ZIP and Compressed Archives

ZIP files are often used to bundle multiple files together, but they have a counterintuitive problem: some file types do not benefit from ZIP compression. JPEG images, MP4 videos, and MP3 audio files are already compressed, so ZIPping them barely changes their size. If you have a folder of JPEG photos totaling 50 MB, ZIPping them might result in a 49 MB ZIP file — still too large for email.

If your ZIP file is too large, split it into smaller volumes (e.g., 20 MB each) using WinRAR, 7-Zip, or the macOS Archive Utility. Send multiple emails, each with one volume. The recipient can combine them on their end. Alternatively, compress each file individually first using the tools above, then ZIP the compressed results.

How to Send Large Files Without Email

For files over 25-30 MB, email is simply the wrong tool. Use one of these alternatives instead:

Google Drive

Upload the file to Google Drive (free: 15 GB), right-click and select "Share," then "Copy link." Paste the link into your email. You can set permissions to "Anyone with the link can view" so the recipient does not need a Google account.

WeTransfer

WeTransfer allows free transfers up to 2 GB. Upload your file, enter your email and the recipient's email, and WeTransfer sends a download link. The link expires after 7 days. It is the simplest option for one-off file sharing.

Dropbox

Create a shared link for any file in your Dropbox (free: 2 GB). Paste the link into your email. Dropbox links never expire unless you revoke them.

Microsoft OneDrive

If you have a Microsoft account, OneDrive (free: 5 GB) offers the same share-link functionality built into Outlook and Windows.

Pro Tip: Compress Everything Before Attaching

Even if your file is under the size limit, compressing it before sending is a good habit. Smaller attachments mean:

• Faster upload and download times
• Less storage space used in your and the recipient's mailbox
• Higher likelihood of successful delivery (some mail servers have soft limits below the official maximum)
• Better mobile experience for recipients on limited data plans

Make compression part of your pre-send routine. A quick pass through a compressor takes seconds and saves everyone time and bandwidth.

Compress Your Files Free

No matter what type of file you need to send, we have a free tool to shrink it. Use our PDF Compressor for documents, Image Compressor for photos, or Video Compressor for clips. All tools run in your browser — your files are never uploaded anywhere.