C-Series Envelope Sizes Explained
The C-series is designed specifically for envelopes — each C-size fits the corresponding A-size unfolded. For example, a C4 envelope fits a full A4 sheet, and a C5 fits an A5 sheet.
📊 C-Series Quick Facts:
• Largest: C0 (917 × 1297 mm)
• Most Used: C4, C5, DL
• Smallest: C10 (28 × 40 mm)
• Unique: DL size (110 × 220 mm)
• Largest: C0 (917 × 1297 mm)
• Most Used: C4, C5, DL
• Smallest: C10 (28 × 40 mm)
• Unique: DL size (110 × 220 mm)
📏 Complete C-Series Dimensions
| Size | Millimetres | Inches | Fits |
|---|---|---|---|
| C0 | 917 × 1297 mm | 36.1 × 51.1 in | A0 |
| C1 | 648 × 917 mm | 25.5 × 36.1 in | A1 |
| C2 | 458 × 648 mm | 18.0 × 25.5 in | A2 |
| C3 | 324 × 458 mm | 12.8 × 18.0 in | A3 |
| C4 | 229 × 324 mm | 9.0 × 12.8 in | A4 |
| C5 | 162 × 229 mm | 6.4 × 9.0 in | A5 |
| C6 | 114 × 162 mm | 4.5 × 6.4 in | A6 |
| C7 | 81 × 114 mm | 3.2 × 4.5 in | A7 |
| C8 | 57 × 81 mm | 2.2 × 3.2 in | A8 |
| C9 | 40 × 57 mm | 1.6 × 2.2 in | A9 |
| C10 | 28 × 40 mm | 1.1 × 1.6 in | A10 |
| DL | 110 × 220 mm | 4.3 × 8.7 in | 1/3 A4 |
🔁 Convert Between C-Series Sizes
C0 → C1
Half
C1 → C0
Double
C1 → C2
Half
C2 → C1
Double
C2 → C3
Half
C3 → C2
Double
C3 → C4
Half
C4 → C3
Double
C4 → C5
Half
C5 → C4
Double
C5 → C6
Half
C6 → C5
Double
DL → C4
Compare
📮 Which Envelope Fits Which Paper?
- C4: Fits an unfolded A4 sheet — ideal for business letters
- C5: Fits an unfolded A5 sheet or A4 folded once
- C6: Fits an A6 card or A4 folded into quarters
- DL: Fits an A4 sheet folded into thirds — the classic business envelope
Common Uses of C-Series Sizes
- C0–C3: Large document mailers, certificates
- C4: Business correspondence, A4 documents
- C5: Greeting cards, invitations, A5 documents
- C6: Small cards, thank-you notes
- DL: Standard business letters, invoices