C4 holds A4 · C5 holds A5 · C6 holds A6 · DL holds A4 folded in thirds.
C-size = A-size + 5-10% for clearance · DL = ⅓ × A4C-series envelopes are sized to hold A-series paper with a small clearance for easy insertion.
📊 Standard Envelope Sizes
Complete reference for standard envelope sizes with dimensions and the paper they fit.
📬 Envelope Size Guide & Examples
Understanding envelope sizes is essential for professional mail, invitations, and business correspondence. Here's a comprehensive guide to help you choose the right envelope for your needs.
🎯 Choosing the Right Envelope Size
- C4 (229×324 mm): The standard business envelope for A4 documents without folding. Used for professional mail, contracts, and official correspondence.
- C5 (162×229 mm): Perfect for A5 paper, flyers, and smaller documents. Commonly used for invitations and brochures.
- C6 (114×162 mm): Ideal for A6 paper, small invitations, and greeting cards. Popular for personal correspondence and thank-you notes.
- DL (110×220 mm): The most common business envelope for A4 paper folded in thirds. Used for invoices, statements, and daily correspondence.
- A2 (89×127 mm): Small envelope for A6 paper folded or small cards. Used for RSVP cards and small announcements.
- #10 (120×160 mm): Standard US business envelope. Used for commercial mail and invoices.
📐 C‑Series vs. DL vs. US Sizes
- C‑Series: ISO standard envelopes designed to hold A‑series paper without folding. C4 holds A4, C5 holds A5, C6 holds A6.
- DL: A popular business envelope size. Holds A4 paper folded in thirds (⅓ of A4). Widely used in Europe and worldwide.
- US Sizes: #10 (4.7×6.3 in), A2 (3.5×5.0 in), A6 (4.1×5.8 in). Used primarily in North America.
💡 Professional Tips for Envelope Sizing
🎯 Paper Compatibility
Always check that your envelope size matches the paper you're sending. C4 holds A4, C5 holds A5, DL holds A4 folded in thirds.
📐 Allowance for Clearance
C‑series envelopes are designed with 5-10% extra space for easy insertion. Always account for slight clearance when choosing envelopes.
💰 Mailing Costs
Different envelope sizes may affect postage costs. Check with your postal service for size-based pricing and weight restrictions.
📬 Envelope Quality
Choose the right paper weight for your envelopes. 80-100 GSM is standard for business envelopes, while 120-160 GSM is used for premium invitations.
❓ Frequently Asked Questions (Envelope Size Calculator)
Q: What size envelope do I need for A4 paper?
A: Use a C4 envelope (229×324 mm) for A4 paper without folding. For folded A4, use DL (110×220 mm).
Q: What is the most common business envelope size?
A: C4 (229×324 mm) and DL (110×220 mm) are the most common business envelope sizes worldwide.
Q: What size envelope fits A5 paper?
A: C5 envelope (162×229 mm) fits A5 paper perfectly without folding.
Q: What is a DL envelope?
A: DL (Dimension Lengthwise) is 110×220 mm and holds A4 paper folded in thirds.
Q: What is the US standard business envelope size?
A: The #10 envelope (120×160 mm / 4.7×6.3 in) is the US standard business envelope.
Q: How do I know what envelope size to use?
A: Use the paper size as a guide. C4 for A4, C5 for A5, C6 for A6, DL for A4 folded in thirds.
Q: What is the difference between C4 and DL?
A: C4 holds A4 without folding (229×324 mm). DL holds A4 folded in thirds (110×220 mm).
Q: What is the best envelope for invitations?
A: C5 (162×229 mm) and C6 (114×162 mm) are popular for invitations. C5 is larger, C6 is smaller.
Q: What is the envelope size for greeting cards?
A: C6 (114×162 mm) is the standard size for greeting cards and small invitations.
📈 Why Accurate Envelope Sizing Matters
Accurate envelope sizing is essential for professional mail, invitations, and business correspondence. Using the wrong envelope size can lead to documents not fitting properly, increased postage costs, and a less professional appearance. This tool ensures your envelopes are the right size for your needs.
🌐 Global Envelope Size Standards
The ISO 216 C‑series is the global standard for envelope sizes in most countries. The US uses its own standards (#10, A2, A6). This tool supports both international and US standards for maximum flexibility.
🔗 Explore More Mail & Print Tools
Check out our other tools: C4 to C3, C5 to C4, C6 to C5, C3 to C2, DL to C4, C4 to DL, Poster Size Calculator, and A4 to Pixels. All designed to make your print and mail workflows smoother.