Email Attachment Size Checker
Check email attachment size limits for Gmail, Outlook, Yahoo, Apple Mail, and 12+ providers. Includes a file size calculator with Base64 encoding overhead, blocked file type reference, and tips for sending large files.
Check Your Attachment Size
Enter your file details to see which email providers can handle it. Remember: email encoding (Base64) adds ~37% to the actual file size.
Attachment Limits by Email Provider
Gmail
Large files: Google Drive (up to 10GB via link)
Auto-converts attachments over 25MB to a Google Drive link. Blocks executable files (.exe, .bat, etc.) even inside ZIP files.
Google Workspace
Large files: Google Drive (up to 5TB via link, depending on plan)
Same attachment limits as consumer Gmail. Admin can restrict certain file types. Drive sharing limits depend on storage plan.
Outlook.com (Hotmail)
Large files: OneDrive (up to 2GB via link)
Slightly smaller than Gmail at 20MB. OneDrive integration for larger files. Blocks dangerous file types.
Microsoft 365 (Exchange Online)
Large files: OneDrive/SharePoint
Default is 35MB but admin can increase up to 150MB. Receiving server must also accept the size. Many orgs keep it at 25-35MB.
Apple iCloud Mail
Large files: Mail Drop (up to 5GB, expires after 30 days)
Mail Drop automatically kicks in for attachments over 20MB. Links expire after 30 days. Works from Apple Mail and iCloud.com.
Yahoo Mail
Large files: Dropbox integration available
25MB limit with no built-in cloud fallback. Use Dropbox or another service for larger files.
ProtonMail
Large files: None built-in
25MB limit. All attachments are encrypted. No cloud storage integration — use separate file sharing for large files.
Zoho Mail
Large files: Zoho WorkDrive
Free plan: 20MB. Paid plans: up to 40MB. Can send files via Zoho WorkDrive links for larger files.
AOL Mail
Large files: None
25MB limit. No cloud storage integration. Consider the recipient's provider limit too.
Mailchimp
Large files: None (use hosted links instead)
Attachments are discouraged in marketing emails — they increase spam score. Use download links hosted on your website instead.
SendGrid
Large files: None
30MB limit via API. Attachments in marketing emails hurt deliverability. Use hosted links for downloads.
Sequenzy
Large files: Use hosted links
Supports attachments in transactional emails. For marketing campaigns, we recommend hosting files and linking to them instead of attaching.
Blocked vs Safe File Types
These file types are accepted by all major email providers. They're the safest options for email attachments.
The gold standard for email attachments. Universally supported. Compress if over 5MB.
Word documents. Widely accepted. Some security-conscious recipients may be wary.
Excel spreadsheets. Accepted everywhere. Large datasets can push file size limits.
PowerPoint files. Can be very large due to embedded images. Compress images before sending.
Standard image formats. JPEG for photos, PNG for graphics. Compress before attaching.
Comma-separated values. Universally accepted and lightweight. Great for data sharing.
ZIP files with safe contents (documents, images) are accepted. Gmail scans contents.
Plain text files. Accepted everywhere. Cannot contain malware. The safest file type.
Tips for Sending Large Files
Compress before sending
ZIP files can reduce size by 50-80% for documents and images. Use 7-Zip or the built-in OS compression tool. For images, use tools like TinyPNG or ImageOptim.
Use cloud storage links
Upload to Google Drive, Dropbox, or OneDrive and share a link. The recipient downloads at their convenience, and you avoid email size limits entirely.
Compress images separately
High-res photos from phones can be 5-15MB each. Resize to reasonable dimensions (1920px max width) and compress to 80% quality. You'll barely notice the difference.
Split large archives
If you must send a large archive via email, split it into parts under 20MB each. 7-Zip can do this automatically. Send parts in separate emails.
Consider the recipient's limit
Even if your provider allows 25MB, the recipient's server might have a 10MB limit. For B2B emails, assume a 20MB maximum to be safe.
Use PDF instead of PPTX/DOCX
Convert presentations and documents to PDF before sending. PDFs are typically smaller, can't be accidentally edited, and are universally viewable without specific software.
Attachments in Marketing Emails — Why You Shouldn't
If you're sending marketing or newsletter emails, don't attach files. Here's why:
Spam filters flag attachments
Mass emails with attachments are a classic spam pattern. Spam filters give attachment-heavy emails higher spam scores, meaning more of your emails land in junk.
Slower delivery
A 5MB attachment × 10,000 subscribers = 50GB of data to transmit. This slows delivery and can overwhelm your sending infrastructure.
No tracking
You can't track attachment downloads. With a hosted link, you get click tracking and can see exactly who downloaded your content.
Better approach: Host & link
Upload your file to your website or cloud storage. Include a download button in your email. You get click tracking, faster delivery, and no spam filter issues.
Like this tool? Try Sequenzy for free
AI-powered email marketing with Stripe integration, automations, and built-in analytics.
About this tool
Every email provider has different attachment size limits, and hitting them causes frustrating bounce-backs. Gmail caps at 25MB, Outlook at 20MB, and when you factor in Base64 encoding overhead (which adds ~37% to your file size), a 19MB file can already be too large for some providers.
This tool lets you check your file size against every major email provider's limits instantly. It accounts for Base64 encoding — the conversion that happens behind the scenes when you attach binary files to email — so you get an accurate picture of whether your attachment will make it through.
You'll also find a complete reference of which file types get blocked (executables, scripts, disk images), which are always safe (PDFs, images, documents), and why marketing emails should never include attachments in the first place.
If you're building email campaigns, our email size checker helps you make sure the total email (HTML + images) stays under clipping thresholds. For signature images, check our signature size guide, and for campaign header images, see our email banner size guide. Our deliverability score tool can help you check if attachments are affecting your sender reputation.
Frequently Asked Questions
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