✉️ C6 Envelope
| Millimeters | 114 × 162 mm |
| Centimeters | 11.4 × 16.2 cm |
| Inches | 4.49 × 6.38 in |
| Points | 323 × 459 pt |
| Picas | 26.9 × 38.3 pc |
| Pixels (300dpi) | 1346 × 1913 px |
| Pixels (72ppi) | 323 × 459 px |
✉️ C5 Envelope
| Millimeters | 162 × 229 mm |
| Centimeters | 16.2 × 22.9 cm |
| Inches | 6.38 × 9.02 in |
| Points | 459 × 649 pt |
| Picas | 38.3 × 54.1 pc |
| Pixels (300dpi) | 1913 × 2705 px |
| Pixels (72ppi) | 459 × 649 px |
Area: 1 C5 = 2 × C6 (C5 is double the area). Scaling factor: √2 ≈ 1.4142 per side.
C5 is the go-to size for invitations, flyers, and standard mail — this tool helps you scale up from C6 for professional correspondence.
C5 (area) = C6 × 0.5 · Scale factor = √2 ≈ 1.4142 per side1 C5 envelope has twice the area of 1 C6 envelope.
📏 What is C6 Envelope Size?
C6 is a small envelope size in the ISO 216 C-series. Its dimensions are 114 × 162 mm (4.5 × 6.4 inches), with an area of 0.018 m². C6 is designed to hold A6 paper without folding (A6 is 105 × 148 mm). It's commonly used for invitations, greeting cards, and personal correspondence. C6 is exactly half the area of C5, making it a popular choice for small mail and stationery.
📄 What is C5 Envelope Size?
C5 is a medium envelope size in the ISO 216 C-series. Its dimensions are 162 × 229 mm (6.4 × 9.0 inches), with an area of 0.037 m². C5 is designed to hold A5 paper without folding (A5 is 148 × 210 mm). It's the go-to size for invitations, flyers, standard mail, and professional correspondence. C5 is exactly double the area of C6, making it a natural step up for more detailed content.
🧮 The Math: How C6 Becomes C5
The ISO 216 C-series is based on the geometric mean of the A and B-series. Each step up (C6 → C5) doubles the area. The side lengths increase by a factor of √2 ≈ 1.4142.
- Width: 114 mm × √2 ≈ 162 mm
- Height: 162 mm × √2 ≈ 229 mm
- Area: 0.018 m² × 2 = 0.037 m²
Formula: 1 C5 = 2 × C6 (in area). So, if you have 2 C6 envelopes, they can be combined to form 1 C5 envelope (or 1 C6 = 0.5 C5).
📊 Quick Conversion Table: C6 to C5
| C6 Envelopes | C5 Equivalent | Scale factor (side) | Real‑world use |
|---|---|---|---|
| 0.5 C6 | 0.25 C5 | 100% | Small invitation |
| 1 C6 | 0.5 C5 | 141.4% (enlarge) | Standard invitation card |
| 2 C6 | 1 C5 | 200% (double width/height) | Full invitation |
| 4 C6 | 2 C5 | 282.8% | Two-page invitation |
| 5 C6 | 2.5 C5 | 316.2% | Small booklet |
| 10 C6 | 5 C5 | 447.2% | Flyer set |
| 25 C6 | 12.5 C5 | 707.1% | Bulk mailing |
| 50 C6 | 25 C5 | 1000% | Large mail campaign |
✉️ Real‑World Examples: C6 to C5 in Action
- 💌 Invitations & Greeting Cards: C6 is the classic invitation envelope size. When you need to scale up to C5 for more elaborate invitations, this converter tells you exactly how many C6 cards fit into a C5 layout.
- 📬 Standard Mail: C6 is used for small mail and personal correspondence. C5 is used for professional mail and larger communications. Understanding the scaling helps with consistent branding.
- 🖨️ Printing & Production: C6 to C5 conversion is essential for print production, especially when printing multiple envelope sizes from the same sheet.
- 📋 Stationery: C6 is used for small stationery sets. C5 is used for letterheads and larger correspondence.
- 🎨 Art & Photography: C6 prints are popular for small art pieces and postcards. C5 offers a larger format for exhibition catalogs and portfolios.
💡 Professional Tips for C6 to C5 Scaling
🎯 Resolution & Quality
When scaling from C6 to C5, if your original is 300 DPI, the resulting C5 will be ~212 DPI — still acceptable for most printing. For high-quality prints, design at 600 DPI at C6 to get ~424 DPI at C5.
📐 C‑Series vs. A‑Series
C-series envelopes are designed to fit A-series paper. C6 is designed to hold A6 paper (105 × 148 mm) without folding. C5 holds A5 paper (148 × 210 mm) without folding.
💰 Printing & Mailing Efficiency
Printing 2 C6 envelopes from 1 C5 sheet can save paper and costs. Many professional printers support C-series sizes — check your printer settings.
📂 Professional Correspondence
C5 is the standard for professional mail and invitations. Use this converter to plan your envelope sizes for professional communications.
❓ Frequently Asked Questions (C6 to C5)
Q: How many C6 envelopes equal 1 C5?
A: Exactly 2 C6 envelopes make 1 C5 in terms of area. You can fit two C6 pages on one C5 sheet.
Q: What is the scaling factor from C6 to C5?
A: Each side is scaled by √2 ≈ 1.4142, meaning you enlarge the width and height by 41.4%.
Q: Can I fit a C6 document into a C5 envelope?
A: Yes, by scaling it up to 141.4% on each dimension. The document will fit, with more white space around it.
Q: What is the difference in area between C6 and C5?
A: C5 has exactly double the area of C6 (0.037 m² vs. 0.018 m²).
Q: Is C6 bigger than C5?
A: No, C5 is larger. C5 is the next size up from C6. 1 C5 = 2 × C6.
Q: What is C6 used for?
A: C6 is used for invitations, greeting cards, personal correspondence, and small mail.
Q: What is C5 used for?
A: C5 is used for invitations, flyers, standard mail, and professional correspondence.
Q: Can I print C6 on C5?
A: Yes, by scaling up to 141.4%. Most printers support this scaling. This tool helps you understand the exact ratio.
Q: What is the C‑series used for?
A: C‑series envelopes are designed for flat mail and professional correspondence, holding A‑series paper without folding.
📈 Why Accurate C6‑to‑C5 Conversion Matters
Accurate scaling between C6 and C5 is essential for professional mail, envelope production, and document management. Whether you're preparing an invitation, designing a flyer, or planning a mailing campaign, this tool ensures your envelopes fit perfectly every time. Inaccurate scaling can lead to wasted paper, misaligned designs, and costly reprints.
🌐 Global Standards & Professional Usage
The C‑series (ISO 216) is used alongside the A‑series and B‑series in many countries. C‑series envelopes are specifically designed for flat mail and professional correspondence. C6 and C5 are the most common sizes for invitations and standard mail. This tool supports professional envelope size conversions for users worldwide.
📐 The Full C‑Series Hierarchy
- C8 = 64 × 91 mm – small correspondence
- C7 = 91 × 128 mm – small envelopes, invitations
- C6 = 114 × 162 mm – standard invitations, greeting cards
- C5 = 162 × 229 mm – medium envelopes, flyers, professional mail
- C4 = 229 × 324 mm – standard mail, A4 documents, business envelopes
- C3 = 324 × 458 mm – large mail, catalogs, A3 documents
- C2 = 458 × 648 mm – oversized mail, A2 documents
- C1 = 648 × 917 mm – very large mail, posters
- C0 = 917 × 1297 mm – extremely large mail, display
Each step up doubles the area, making the system intuitive and easy to scale.
🔗 Explore More Envelope & Mail Tools
Check out our other converters: C5 to C4, C5 to C6, C4 to C3, C3 to C2, C2 to C3, DL to C4, and C4 to DL. All designed to make your print and mail workflows smoother.