Mailing documents requires the perfect pairing between paper and envelope. Our Envelope Size Calculator helps you choose the correct ISO C-Series or North American envelope for your needs. Whether you're sending an unfolded A4 certificate in a C4 envelope or a tri-folded Letter in a #10 business envelope, our tool ensures your stationary is professional and correctly sized for the post.
Privacy Protected
Standard Envelope Size Chart
Find the correct envelope size (C4, C5, C6, DL) for your paper dimensions. Fast, free, and 100% private. All processing happens locally.
Share Tool
About Standard Envelope Size Chart
1
Enter Paper Size
Select the paper you want to mail (e.g., A4).
2
See Envelope
The tool recommends the appropriate envelope size.
3
Review Results
Verify the output looks correct before using or downloading it.
4
Save Your Output
Click the download or copy button to export your results to your device or clipboard.
Key Features
Paper-to-Envelope Mapping
Matches your document size (unfolded, half-folded, or tri-folded) to the correct envelope.
C-Series ISO Support
Complete dimensions for the international C4, C5, C6 and DL standards.
Business Envelope Guide
Includes North American standards like the #10, #9, and invitation (A-series) sizes.
Frequently Asked Questions
A C4 envelope fits an unfolded A4 sheet. A C5 fits an A4 folded in half.
Related Tools
View allLast updated on