✉️ 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 |
✉️ 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 |
Area: 1 C5 = 2 × C6 (C6 is half the area). Scaling factor: 1/√2 ≈ 0.7071 per side.
C6 is the classic invitation and stationery envelope size — this tool helps you scale down from C5 for professional mail and correspondence.
C6 = C5 × 2 · Scale factor = 1/√2 ≈ 0.7071 per side1 C5 envelope splits into exactly 2 C6 envelopes (or 1 C6 = 0.5 C5).
📏 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 commonly used for professional mail, invitations, flyers, and brochures. C5 is exactly double the area of C6, making it a popular choice for medium-sized documents and marketing materials.
📄 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 0.0185 m². C6 is designed to hold A6 paper without folding (A6 is 105 × 148 mm). It's the classic size for invitations, greeting cards, thank-you notes, and personal correspondence. C6 is exactly half the area of C5, making it a perfect choice for small-format stationery.
🧮 The Math: How C5 Becomes C6
The ISO 216 C-series is based on the geometric mean of the A and B-series. Each step down (C5 → C6) halves the area. The side lengths decrease by a factor of 1/√2 ≈ 0.7071.
- Width: 162 mm × (1/√2) ≈ 114 mm
- Height: 229 mm × (1/√2) ≈ 162 mm
- Area: 0.037 m² ÷ 2 = 0.0185 m²
Formula: 1 C5 = 2 × C6 (in area). So, if you have 1 C5 envelope, you can create 2 C6 envelopes from it (or 1 C6 = 0.5 C5).
📊 Quick Conversion Table: C5 to C6
| C5 Envelopes | C6 Equivalent | Scale factor (side) | Real‑world use |
|---|---|---|---|
| 0.5 C5 | 1 C6 | 100% | Single invitation envelope |
| 1 C5 | 2 C6 | 70.7% (reduce) | Two invitation envelopes |
| 2 C5 | 4 C6 | 50% (half width/height) | Four greetings cards |
| 5 C5 | 10 C6 | 31.6% | Stationery set |
| 10 C5 | 20 C6 | 22.4% | Bulk invitations |
| 25 C5 | 50 C6 | 14.1% | Large stationery order |
| 50 C5 | 100 C6 | 10% | Massive invitation mail |
| 100 C5 | 200 C6 | 7.1% | Commercial mailing |
✉️ Real‑World Examples: C5 to C6 in Action
- 💌 Invitations & Announcements: C5 is often used for premium invitations and announcements. When you need to produce standard C6 reply envelopes and thank-you notes, this converter tells you exactly how many C6 envelopes you can create from each C5 envelope.
- 📬 Marketing Materials: C5 flyers and brochures can be designed, and then the same artwork can be scaled to C6 for smaller-format handouts or mailers.
- 🎄 Greeting Cards: C5 is used for larger greeting cards and holiday cards. C6 is used for standard thank-you notes and small cards. Convert between them for consistent branding.
- 🏢 Office Correspondence: C5 is used for professional letters and documents. C6 is used for small notes and internal correspondence. Convert between them for consistent document management.
- 🖨️ Printing & Production: Understanding C5 to C6 conversion is essential for print production, especially when printing multiple envelope sizes from the same sheet.
💡 Professional Tips for C5 to C6 Scaling
🎯 Resolution & Quality
When scaling from C5 to C6, if your original is 300 DPI, the resulting C6 will be ~424 DPI — actually higher quality! This is because you're concentrating the same pixels into a smaller area. For best results, design at 300 DPI at C5 for sharp C6 prints.
📐 C‑Series vs. A‑Series
C-series envelopes are designed to fit A-series paper. C5 is designed to hold A5 paper (148 × 210 mm) without folding. C6 holds A6 paper (105 × 148 mm) without folding. This makes C6 a common choice for invitations and stationery.
💰 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 for "scale to fit" options.
📂 Professional Correspondence
C6 is the standard for invitations, greetings, and personal correspondence. Use this converter to plan your envelope sizes for professional communications.
❓ Frequently Asked Questions (C5 to C6)
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 envelopes on one C5 sheet.
Q: What is the scaling factor from C5 to C6?
A: Each side is scaled by 1/√2 ≈ 0.7071, meaning you reduce the width and height by 29.3%.
Q: Can I fit a C5 document into a C6 envelope?
A: Yes, by scaling it down to 70.7% on each dimension. The document will fit, but text and details will be smaller.
Q: What is the difference in area between C5 and C6?
A: C5 has exactly double the area of C6 (0.037 m² vs. 0.0185 m²).
Q: Is C5 bigger than C6?
A: Yes, C5 is larger. C5 is the next size up from C6. 1 C5 = 2 × C6.
Q: What is C5 used for?
A: C5 is used for flyers, brochures, professional invitations, and medium-sized documents.
Q: What is C6 used for?
A: C6 is used for invitations, greeting cards, thank-you notes, and personal correspondence.
Q: Can I print C5 on C6?
A: Yes, by scaling down to 70.7%. 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 C5‑to‑C6 Conversion Matters
Accurate scaling between C5 and C6 is essential for professional mail, envelope production, and stationery design. Whether you're preparing invitations, designing greeting cards, 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. C5 and C6 are the most common sizes for invitations, greetings, and stationery worldwide. This tool supports professional envelope size conversions for users across the globe.
📐 The Full C‑Series Hierarchy
- C8 = 64 × 91 mm – small correspondence
- C7 = 91 × 128 mm – small envelopes, invitations
- C6 = 114 × 162 mm – invitations, greeting cards, stationery
- C5 = 162 × 229 mm – flyers, brochures, professional invitations
- 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: C6 to C5, C5 to C4, C4 to C5, C4 to C3, C3 to C4, C2 to C3, DL to C4, and C4 to DL. All designed to make your print and mail workflows smoother.