Area: 1 C1 = 2 × C2 (C2 is half the area). Scaling factor: 1/√2 ≈ 0.7071 per side.
C-series is designed for envelopes and packaging — this tool helps you scale between C1 and C2 for professional envelope and printing applications.
C2 = C1 × 0.5 · Scale factor = 1/√2 ≈ 0.7071 per side1 C1 sheet splits into exactly 2 C2 sheets (or 1 C2 = 0.5 C1).
📏 What is C1 Paper Size?
C1 is a large paper size in the ISO 269 C-series. Its dimensions are 648 × 917 mm (25.5 × 36.1 inches), with an area of 0.594 m². C1 is primarily used for large envelopes, packaging, and professional printing applications. The C-series is designed specifically for envelope making, with each C size being slightly larger than the corresponding A size to accommodate folded A-series documents. C1 is exactly double the area of C2, making it a key size in the envelope production chain.
📄 What is C2 Paper Size?
C2 is a medium-large paper size in the ISO 269 C-series. Its dimensions are 458 × 648 mm (18.0 × 25.5 inches), with an area of 0.297 m². C2 is widely used for large envelopes, professional mailings, and packaging materials. It's designed to accommodate A2 documents (420 × 594 mm) when folded. C2 is exactly half the area of C1, making it a natural step down for smaller envelope applications.
🧮 The Math: How C1 Becomes C2
The ISO 269 C-series is based on the geometric mean between A-series and B-series sizes. Each step down (C1 → C2) halves the area. The side lengths decrease by a factor of 1/√2 ≈ 0.7071.
- Width: 648 mm × (1/√2) ≈ 458 mm
- Height: 917 mm × (1/√2) ≈ 648 mm
- Area: 0.594 m² ÷ 2 = 0.297 m²
Formula: 1 C1 = 2 × C2 (in area). So, if you have 1 C1 sheet, you can make 2 C2 sheets from it (or 1 C2 = 0.5 C1).
📊 Quick Conversion Table: C1 to C2
| C1 Sheets | C2 Equivalent | Scale factor (side) | Real‑world use |
|---|---|---|---|
| 0.5 C1 | 1 C2 | 100% (C2 = half C1) | Single large envelope |
| 1 C1 | 2 C2 | 70.7% (reduce) | Two large envelopes |
| 2 C1 | 4 C2 | 50% (half width/height) | Multiple envelope production |
| 5 C1 | 10 C2 | 31.6% | Small batch envelope printing |
| 10 C1 | 20 C2 | 22.4% | Medium envelope run |
| 25 C1 | 50 C2 | 14.1% | Large envelope production |
| 50 C1 | 100 C2 | 10% | Commercial envelope order |
| 100 C1 | 200 C2 | 7.1% | Massive envelope manufacturing |
🖨️ Real‑World Examples: C1 to C2 in Action
- 📬 Envelope Production: C1 is used for large envelopes and packaging materials. When you need to produce C2 envelopes for smaller items, this converter tells you exactly how many C2 envelopes you can make from each C1 sheet.
- 📦 Packaging Design: C1 is used for large packaging and display materials. C2 is used for smaller packaging and mailers. Understanding the scaling helps with production planning.
- 🖨️ Professional Printing: C1 is used for large-format printing projects. C2 is used for smaller professional publications and envelope printing.
- 📋 Stationery & Office: C1 is used for large office documents and presentations. C2 is used for medium-format stationery and envelope products.
- 🎨 Art & Photography: C1 prints are used for large-format art pieces. C2 offers a more manageable size for portfolios and catalogs.
💡 Professional Tips for C1 to C2 Scaling
🎯 Resolution & Quality
When reducing from C1 to C2, if your original is 300 DPI, the resulting C2 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 C1 for sharp C2 prints.
📐 C‑Series vs. A‑Series
C-series sizes are designed to accommodate A-series documents in envelopes. For example, C1 envelopes fit A1 documents (594 × 841 mm) when folded. Understanding the relationship between C and A sizes is essential for professional envelope production.
💰 Envelope Production Efficiency
Printing 2 C2 envelopes from 1 C1 sheet can save paper and costs. Many professional envelope manufacturers use this scaling for efficient production.
📂 Packaging & Mailing
C1 is often used for large packaging and display materials. C2 is used for smaller mailers and product packaging. Understanding the conversion helps with inventory planning.
❓ Frequently Asked Questions (C1 to C2)
Q: How many C2 sheets equal 1 C1?
A: Exactly 2 C2 sheets make 1 C1 in terms of area. You can fit two C2 pages on one C1 sheet.
Q: What is the scaling factor from C1 to C2?
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 C1 document onto a C2 sheet?
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 C1 and C2?
A: C1 has exactly double the area of C2 (0.594 m² vs. 0.297 m²).
Q: Is C1 bigger than C2?
A: Yes, C1 is larger. C1 is the next size up from C2. 1 C1 = 2 × C2.
Q: What is C1 used for?
A: C1 is used for large envelopes, packaging, professional printing, and large-format documents.
Q: What is C2 used for?
A: C2 is used for large envelopes, medium packaging, mailers, and professional printing.
Q: How does C‑series compare to A‑series?
A: C-series sizes are designed for envelopes and are slightly larger than A-series at the same number. For example, C1 is larger than A1.
Q: What comes after C1?
A: C0 is the next size up (917 × 1297 mm). C2 is the next size down.
📈 Why Accurate C1‑to‑C2 Conversion Matters
Accurate scaling between C1 and C2 is essential for envelope production, packaging design, and professional printing. Whether you're preparing large envelopes, designing packaging, or planning a print run, this tool ensures your materials fit perfectly every time. Inaccurate scaling can lead to wasted paper, misaligned envelopes, and costly reprints.
🌐 Global Standards & Professional Usage
The C‑series (ISO 269) is used alongside the A‑series and B‑series in many countries. C-series sizes are specifically designed for envelopes and packaging, making them essential for professional mailing and printing applications. This tool supports professional paper size conversions for users worldwide.
📐 The Full C‑Series Hierarchy
- C8 = 81 × 114 mm – small envelopes for C8 documents
- C7 = 114 × 162 mm – small envelopes for C7 documents
- C6 = 162 × 229 mm – standard envelopes for C6 documents
- C5 = 229 × 324 mm – large envelopes for C5 documents
- C4 = 324 × 458 mm – large envelopes for C4 documents
- C3 = 458 × 648 mm – extra large envelopes for C3 documents
- C2 = 458 × 648 mm – large envelopes for C2 documents
- C1 = 648 × 917 mm – very large envelopes for C1 documents
- C0 = 917 × 1297 mm – massive envelopes for C0 documents
Each step up doubles the area, making the system intuitive and easy to scale.
🔗 Explore More Paper & Envelope Tools
Check out our other converters: C2 to C3, C3 to C4, C4 to C5, A4 to A3, Letter to A4, PX to MM, and DPI Calculator. All designed to make your print, envelope, and design workflows smoother.