✉️ C4 Envelope
| Millimeters | 229 × 324 mm |
| Centimeters | 22.9 × 32.4 cm |
| Inches | 9.02 × 12.76 in |
| Points | 649 × 918 pt |
| Picas | 54.1 × 76.5 pc |
| Pixels (300dpi) | 2705 × 3827 px |
| Pixels (72ppi) | 649 × 918 px |
✉️ C3 Envelope
| Millimeters | 324 × 458 mm |
| Centimeters | 32.4 × 45.8 cm |
| Inches | 12.76 × 18.03 in |
| Points | 918 × 1298 pt |
| Picas | 76.5 × 108.2 pc |
| Pixels (300dpi) | 3827 × 5410 px |
| Pixels (72ppi) | 918 × 1298 px |
Area: 1 C3 = 2 × C4 (double the area). Scaling factor: √2 ≈ 1.4142 per side.
C3 is used for large catalogs and oversized invitations — this tool helps you scale up from C4 for professional mail and correspondence.
C3 (area) = C4 × 0.5 · Scale factor = √2 ≈ 1.4142 per side1 C3 sheet has twice the area of 1 C4 sheet.
📏 What is C4 Envelope Size?
C4 is a medium envelope size in the ISO 216 C-series. Its dimensions are 229 × 324 mm (9.0 × 12.8 inches), with an area of 0.074 m². C4 is designed to hold A4 paper without folding (A4 is 210 × 297 mm). It's the standard envelope size for professional correspondence, business mail, and official documents. C4 is exactly half the area of C3, making it the most common professional envelope size worldwide.
📄 What is C3 Envelope Size?
C3 is a large envelope size in the ISO 216 C-series. Its dimensions are 324 × 458 mm (12.8 × 18.0 inches), with an area of 0.148 m². C3 is designed to hold A3 paper without folding (A3 is 297 × 420 mm). It's commonly used for professional mail, catalogs, large-format correspondence, and oversized invitations. C3 is exactly double the area of C4, making it the ideal size for large documents, presentations, and bulk mailings.
🧮 The Math: How C4 Becomes C3
The ISO 216 C-series is based on the geometric mean of the A and B-series. Each step up (C4 → C3) doubles the area. The side lengths increase by a factor of √2 ≈ 1.4142.
- Width: 229 mm × √2 ≈ 324 mm
- Height: 324 mm × √2 ≈ 458 mm
- Area: 0.074 m² × 2 = 0.148 m²
Formula: 1 C3 = 2 × C4 (in area). So, if you have 2 C4 envelopes, they can be combined to form 1 C3 envelope (or 1 C4 = 0.5 C3).
📊 Quick Conversion Table: C4 to C3
| C4 Envelopes | C3 Equivalent | Scale factor (side) | Real‑world use |
|---|---|---|---|
| 0.5 C4 | 0.25 C3 | 100% | Small mailer |
| 1 C4 | 0.5 C3 | 141.4% (enlarge) | Standard business envelope |
| 2 C4 | 1 C3 | 200% (double width/height) | Large catalog envelope |
| 4 C4 | 2 C3 | 282.8% | Bulk mailing bundle |
| 5 C4 | 2.5 C3 | 316.2% | Professional presentation |
| 10 C4 | 5 C3 | 447.2% | Large mailing campaign |
| 25 C4 | 12.5 C3 | 707.1% | Bulk marketing mailer |
| 50 C4 | 25 C3 | 1000% | Large-scale mailing |
✉️ Real‑World Examples: C4 to C3 in Action
- 📦 Professional Mail: C4 is the standard for business correspondence and official documents. When you need to scale up to C3 for larger documents or special deliveries, this converter tells you exactly how many C4 envelopes fit into a C3 layout.
- 💌 Invitations & Announcements: C4 is used for standard invitations and formal announcements. C3 is used for premium oversized invitations and announcements. Understanding the scaling helps with consistent branding.
- 📬 Marketing Materials: C4 flyers are common for professional handouts. C3 offers more space for detailed marketing content.
- 🏢 Office Correspondence: C4 is used for business letters and official documents. C3 is used for larger presentations and reports. Convert between them for consistent document management.
- 🖨️ Printing & Production: Understanding C4 to C3 conversion is essential for print production, especially when printing multiple envelope sizes from the same sheet.
💡 Professional Tips for C4 to C3 Scaling
🎯 Resolution & Quality
When scaling from C4 to C3, if your original is 300 DPI, the resulting C3 will be ~212 DPI — still acceptable for most printing. For high-quality prints, design at 600 DPI at C4 to get ~424 DPI at C3.
📐 C‑Series vs. A‑Series
C-series envelopes are designed to fit A-series paper. C4 is designed to hold A4 paper (210 × 297 mm) without folding. C3 holds A3 paper (297 × 420 mm) without folding. This makes C4 the most common business envelope size.
💰 Printing & Mailing Efficiency
Printing 2 C4 envelopes from 1 C3 sheet can save paper and costs. Many professional printers support C-series sizes — check your printer settings for "scale to fit" options.
📂 Professional Correspondence
C4 is the standard for business mail, official documents, and professional correspondence. Use this converter to plan your envelope sizes for professional communications.
❓ Frequently Asked Questions (C4 to C3)
Q: How many C4 envelopes equal 1 C3?
A: Exactly 2 C4 envelopes make 1 C3 in terms of area. You can fit two C4 envelopes on one C3 sheet.
Q: What is the scaling factor from C4 to C3?
A: Each side is scaled by √2 ≈ 1.4142, meaning you enlarge the width and height by 41.4%.
Q: Can I fit a C4 document into a C3 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 C4 and C3?
A: C3 has exactly double the area of C4 (0.148 m² vs. 0.074 m²).
Q: Is C4 bigger than C3?
A: No, C3 is larger. C3 is the next size up from C4. 1 C3 = 2 × C4.
Q: What is C4 used for?
A: C4 is used for business correspondence, official documents, professional mail, and standard invitations.
Q: What is C3 used for?
A: C3 is used for large catalogs, oversized invitations, professional mail, and large-format correspondence.
Q: Can I print C4 on C3?
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 C4‑to‑C3 Conversion Matters
Accurate scaling between C4 and C3 is essential for professional mail, envelope production, and document management. Whether you're preparing a catalog, designing an invitation, 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. C4 is the most widely used business envelope size globally. 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 = 128 × 182 mm – standard envelopes, invitations
- C5 = 182 × 257 mm – medium envelopes, flyers
- 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: C3 to C2, C3 to C4, C5 to C4, C6 to C5, DL to C4, and C4 to DL. All designed to make your print and mail workflows smoother.