Because ISO paper sizes are designed around a simple principle — halving always preserves the shape — folding is effortless once you know the technique. This guide covers the three most useful folds for A4: A5 (half fold), A6 (quarter fold), and DL (tri-fold).
Half Fold: A4 → A5
Bring one short edge to the other short edge. Result: A5 (148 × 210 mm), fits a C5 envelope. Use for greeting cards, small programmes, quarter-page booklets.
Tip: Score the fold line lightly before folding to prevent cracking on thick stock.
Quarter Fold: A4 → A6
Fold in half to A5, then in half again. Result: A6 (105 × 148 mm), fits a C6 envelope. Use for postcards, invitations, small booklets.
Tri-Fold (DL): A4 → DL
Fold A4 into three equal panels of 99 mm each. Result: 99 × 210 mm, slightly larger than a DL envelope (110 × 220 mm).
Three tri-fold styles:
- Letter fold — one panel folds in, the other folds over. Flap on the outside.
- Roll fold — middle in, top over. Flap enclosed.
- Z-fold — panels alternate like a fan.
Comparison Table
| Fold | Final Size | Panels | Best For |
|---|---|---|---|
| Half fold | A5 (148 × 210 mm) | 2 | Cards |
| Quarter fold | A6 (105 × 148 mm) | 4 | Postcards |
| Letter fold | 99 × 210 mm | 3 | Business letters |
| Roll fold | 99 × 210 mm | 3 | Brochures |
Envelope Compatibility
| Folded Size | Fits Envelope | Envelope Size |
|---|---|---|
| A5 | C5 | 162 × 229 mm |
| A6 | C6 | 114 × 162 mm |
| DL | DL | 110 × 220 mm |
| A4 (flat) | C4 | 229 × 324 mm |
Professional Folding Tips
- Score first for thick paper — 100 gsm and above benefits from scoring.
- Use a bone folder — presses the fold crisply.
- Line up edges precisely — misaligned edges show through the fold.
- Fold away from the score — cleaner appearance.
- Use a folding machine for volume — consistent results for hundreds of sheets.
Frequently Asked Questions
How do I fold A4 into A5?
Bring one short edge to the other short edge. Result is A5 (148 × 210 mm).
How do I fold A4 into DL?
Fold into three equal panels of 99 mm each.
Should I score before folding?
For paper above 100 gsm, yes.
What is a "letter fold"?
A tri-fold where the flap is on the outside.
What is a "roll fold"?
A tri-fold where the flap is enclosed.
Conclusion
Folding A4 into A5, A6, or DL is a basic but essential skill. With a bone folder and a bit of practice, you produce crisp, professional results every time.