The A-series paper sizes are the international standard used in most countries worldwide. Based on the ISO 216 standard, these sizes follow an elegant mathematical system where each size is exactly half of the previous one.
Understanding A-series dimensions is essential for designers working on print projects, from business cards to large-format posters.
The A-Series System
The A-series is built on a simple principle: each size is half the area of the size before it, created by halving the longer edge. This means A1 is half of A0, A2 is half of A1, and so on.
The magic ratio? Each sheet maintains a 1:√2 aspect ratio (approximately 1:1.414), which means scaling between sizes preserves proportions perfectly.
Complete A-Series Reference
Dimensions at a Glance
| Size | mm | Inches | Pixels (300 DPI) | Common Uses |
|---|---|---|---|---|
| A0 | 841 × 1189 | 33.1 × 46.8 | 9933 × 14043 | Technical drawings, large posters |
| A1 | 594 × 841 | 23.4 × 33.1 | 7016 × 9933 | Flip charts, architectural plans |
| A2 | 420 × 594 | 16.5 × 23.4 | 4961 × 7016 | Posters, diagrams |
| A3 | 297 × 420 | 11.7 × 16.5 | 3508 × 4961 | Tabloid-size documents, menus |
| A4 | 210 × 297 | 8.3 × 11.7 | 2480 × 3508 | Standard documents, letters |
| A5 | 148 × 210 | 5.8 × 8.3 | 1748 × 2480 | Notebooks, flyers |
| A6 | 105 × 148 | 4.1 × 5.8 | 1240 × 1748 | Postcards, pocket books |
| A7 | 74 × 105 | 2.9 × 4.1 | 874 × 1240 | Pocket cards, labels |
| A8 | 52 × 74 | 2.0 × 2.9 | 614 × 874 | Small labels, tickets |
| A9 | 37 × 52 | 1.5 × 2.0 | 437 × 614 | Tiny labels |
| A10 | 26 × 37 | 1.0 × 1.5 | 307 × 437 | Stamps, tiny tags |
A0 - The Foundation (841 × 1189 mm)
A0 is the base of the entire system, with an area of exactly 1 square meter. It's the largest standard A-size and the starting point from which all other sizes derive.
Common applications:
- Technical drawings and blueprints
- Large-format posters
- Exhibition displays
- Architectural plans
→ Create an A0 canvas (300 DPI)
→ Create an A0 canvas (100 DPI - faster preview)
A1 - Large Format (594 × 841 mm)
Half of A0, A1 is commonly used for flip charts and large presentation materials.
Common applications:
- Flip chart paper
- Large posters
- Architectural drawings
- Event signage
→ Create an A1 canvas (300 DPI)
→ Create an A1 canvas (100 DPI)
A2 - Poster Size (420 × 594 mm)
A2 is the standard size for wall posters and larger promotional materials.
Common applications:
- Movie posters
- Event posters
- Diagrams and charts
- Small drawings
→ Create an A2 canvas (300 DPI)
→ Create an A2 canvas (100 DPI)
A3 - Tabloid (297 × 420 mm)
A3 bridges the gap between standard documents and posters. It's twice the size of A4 and widely used for professional documents that need more space.
Common applications:
- Tabloid newspapers
- Restaurant menus
- Presentation handouts
- Certificate frames
- Ledger documents
→ Create an A3 canvas (300 DPI)
→ Create an A3 canvas (100 DPI)
A4 - Standard Document (210 × 297 mm)
A4 is the world's most commonly used paper size (except in North America). It's the default for business documents, academic papers, and personal correspondence.
Common applications:
- Business letters
- Academic papers
- Printable forms
- Magazines
- Brochures
- Standard documents
→ Create an A4 canvas (300 DPI)
→ Create an A4 canvas (150 DPI)
A5 - Compact Document (148 × 210 mm)
A5 is half of A4, making it perfect for compact documents and notebooks. It’s slightly taller and narrower than the US “Half Letter” size (5.5 × 8.5"), so treat them as separate templates when designing for international versus US printers.
Common applications:
- Notebooks and journals
- Flyers and leaflets
- Small booklets
- Event programs
- Instruction manuals
- Planners
→ Create an A5 canvas (300 DPI)
A6 - Postcard (105 × 148 mm)
A6 is the standard postcard size in many countries and works well for pocket-sized materials.
Common applications:
- Postcards
- Greeting cards
- Pocket books
- Invitations
- Recipe cards
- Photo prints
→ Create an A6 canvas (300 DPI)
A7 - Pocket Size (74 × 105 mm)
A7 fits comfortably in a pocket, making it ideal for quick reference cards.
Common applications:
- Playing cards (approximate)
- Pocket notebooks
- Business card alternatives
- Reference cards
- Small flyers
→ Create an A7 canvas (300 DPI)
A8 - Mini (52 × 74 mm)
A8 is used for small labels and tickets.
Common applications:
- Event tickets
- Price tags
- Small labels
- Reward cards
→ Create an A8 canvas (300 DPI)
A9 and A10 - Micro Sizes
These tiny sizes (A9: 37 × 52 mm, A10: 26 × 37 mm) are used for stamps, labels, and specialty applications.
→ Create an A9 canvas (300 DPI)
→ Create an A10 canvas (300 DPI)
DPI and Pixel Calculations
When designing for print, DPI (dots per inch) determines quality:
| DPI | Quality | Use Case |
|---|---|---|
| 72 | Screen only | Web graphics |
| 150 | Draft print | Internal documents |
| 300 | Standard print | Professional printing |
| 600 | High quality | Fine art, detailed work |
Pixel calculation formula:
Pixels = (mm × DPI) ÷ 25.4
For example, A4 at 300 DPI:
- Width: (210 × 300) ÷ 25.4 = 2480 pixels
- Height: (297 × 300) ÷ 25.4 = 3508 pixels
Bleed and Safe Areas
When designing for professional printing, add bleed (extra margin that gets trimmed):
Standard bleed: 3mm on all sides
| Size | With 3mm Bleed |
|---|---|
| A4 | 216 × 303 mm |
| A5 | 154 × 216 mm |
| A6 | 111 × 154 mm |
Safe area: Keep important content at least 5mm from trim edges.
A-Series vs Letter Size
While most of the world uses A-series, North America primarily uses Letter size (8.5 × 11 inches / 216 × 279 mm).
Key differences:
- Letter is slightly wider and shorter than A4
- A4 is 210 × 297 mm vs Letter's 216 × 279 mm
- Documents designed for one may not print perfectly on the other
When designing for international audiences, consider creating versions for both.
Scaling Between A-Sizes
The 1:√2 ratio means you can scale designs between A-sizes at these percentages:
| From → To | Scale |
|---|---|
| A4 → A3 | 141% |
| A4 → A5 | 71% |
| A3 → A4 | 71% |
| A5 → A4 | 141% |
This consistent ratio makes the A-series incredibly practical for scaling designs up or down.
Summary
The A-series provides a logical, mathematically elegant system for paper sizes. A4 is your everyday standard, but understanding the full range lets you choose the right size for any project.
Most used sizes:
- A4 (210 × 297 mm): Standard documents
- A3 (297 × 420 mm): Presentations, menus
- A5 (148 × 210 mm): Notebooks, flyers
- A6 (105 × 148 mm): Postcards, cards
Start your next print project with the correct canvas size and ensure professional results every time.
