// free tool
Email Size Calculator
Calculate the total size of your email including headers, body, and attachments. Check if your email exceeds common size limits.
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// how it works
How to use Email Size Calculator
- 01
Enter content
Type or paste your email subject line and body content into the provided fields.
- 02
Add attachments
Enter the total combined size of your attachments in megabytes to include Base64 encoding overhead.
- 03
Review total size
See a detailed size breakdown with warnings if your email exceeds common provider limits.
// features
Why use Email Size Calculator
Gmail clip detection
Warns you when your email body exceeds 102 KB, which causes Gmail to clip the message with a truncation link.
Attachment calculator
Factors in attachment file sizes and automatically adds the Base64 encoding overhead for accurate totals.
Provider limits
Compares your email size against Gmail, Outlook, Yahoo, and corporate mail server limits in real time.
Base64 overhead
Accounts for the 37 percent size increase that Base64 encoding adds to every email attachment.
Instant calculation
Results update in real time as you type, with no button clicks or server requests required.
Privacy first
All calculations happen locally in your browser. Your email content is never sent to any server.
// use cases
Who uses Email Size Calculator
Email marketers
Check campaign emails against Gmail clipping thresholds before sending to ensure full message visibility.
Developers
Estimate MIME message sizes when building email sending systems or debugging delivery issues.
Designers
Verify that HTML email templates with embedded images stay within provider size limits.
Support teams
Confirm that reply emails with attachments will not bounce due to exceeding recipient server limits.