Standard Size Paper- Complete Guide to Paper Dimensions
What Are Standard Paper Sizes?
Paper comes in fixed dimensions. Those dimensions aren't arbitrary—they follow standardized systems used worldwide. If you're printing, designing, or ordering supplies, knowing these sizes saves you from costly mistakes.
Two main systems exist: the ISO 216 system (used everywhere except the US and Canada) and the North American system. They don't play nice together.
The ISO 216 Paper Size System
This system starts with A0 and halves each subsequent size. The ratio stays constant at 1:√2 (approximately 1:1.414). This means if you cut any size in half, you get the next size down with identical proportions.
A Series Sizes
The A series is what most of the world uses. Here's the breakdown:
| Size | Dimensions (mm) | Dimensions (inches) | Typical Use |
|---|---|---|---|
| A0 | 841 × 1189 | 33.1 × 46.8 | Large technical drawings, posters |
| A1 | 594 × 841 | 23.4 × 33.1 | Flip charts, architectural plans |
| A2 | 420 × 594 | 16.5 × 23.4 | Large diagrams, small posters |
| A3 | 297 × 420 | 11.7 × 16.5 | Presentations, diagrams, newsletters |
| A4 | 210 × 297 | 8.3 × 11.7 | Business letters, documents, photocopying |
| A5 | 148 × 210 | 5.8 × 8.3 | Notepads, small booklets, flyers |
| A6 | 105 × 148 | 4.1 × 5.8 | Postcards, small notepads |
| A7 | 74 × 105 | 2.9 × 4.1 | Business cards (some countries) |
| A8 | 52 × 74 | 2.0 × 2.9 | Playing cards, tickets |
A4 is your everyday paper. Almost every office, printer, and document in the world outside North America uses A4. If you're working internationally, A4 is your baseline.
B Series Sizes
B series falls between A sizes. It's used for books, envelopes, and passports.
- B0 = 1000 × 1414 mm
- B1 = 707 × 1000 mm
- B2 = 500 × 707 mm
- B3 = 353 × 500 mm
- B4 = 250 × 353 mm
- B5 = 176 × 250 mm
- B6 = 125 × 176 mm
B5 is common for novels and some international business correspondence. B4 sees use in newspapers and some professional printing.
C Series Sizes
C sizes are for envelopes. A document fits into the envelope one size larger than itself.
- C4 fits unfolded A4 = 229 × 324 mm
- C5 fits unfolded A5 or folded A4 = 162 × 229 mm
- C6 fits unfolded A6 or folded A4 twice = 114 × 162 mm
- C7/C6 fits folded A5 = 81 × 162 mm
North American Paper Sizes
The US uses its own system. Measurements are in inches. No consistent aspect ratio exists between sizes—each was defined independently. This causes problems when converting files.
Common US Sizes
| Size | Dimensions (inches) | Dimensions (mm) | Typical Use |
|---|---|---|---|
| Letter | 8.5 × 11 | 216 × 279 | Business documents, schoolwork |
| Legal | 8.5 × 14 | 216 × 356 | Contracts, legal filings |
| Tabloid | 11 × 17 | 279 × 432 | Newspapers, large spreadsheets |
| Junior Legal | 8 × 5 | 203 × 127 | Some legal documents |
| Ledger | 17 × 11 | 432 × 279 | Accounting, engineering drawings |
Letter size dominates American offices. It's not the same as A4. A4 is slightly taller and narrower. If you design a document in the US and send it to someone using A4 printers, expect trimming or scaling issues.
US Envelope Sizes
- Number 10 envelope = 4.125 × 9.5 inches (holds letter paper folded into thirds)
- Monarch envelope = 3.875 × 7.5 inches (personal correspondence)
- Business envelope = 4.5 × 10.375 inches (official documents)
Other Standard Sizes You Might Encounter
Photo Print Sizes
Photo prints don't follow either standard system. Common sizes include:
- 4×6 inches = 102 × 152 mm (most common)
- 5×7 inches = 127 × 178 mm
- 8×10 inches = 203 × 254 mm
- 11×14 inches = 279 × 356 mm
Digital sensor ratios (like 3:2 for DSLRs or 4:3 for some cameras) don't match these print sizes. Cropping happens. Plan for it.
Book Sizes
Books use their own conventions:
- Digest = 5.5 × 8.5 inches (smaller than letter)
- Mass market paperback = 4.25 × 6.87 inches
- Trade paperback = 5.5 × 8.5 inches
- Hardcover novel = 6 × 9 inches
Why Paper Sizes Matter for Your Work
Wrong paper size wastes money. You either trim down (wasting stock) or your design gets distorted. For print projects, always confirm the exact dimensions before sending files to press.
Graphic designers need to know these sizes cold. If you're creating a brochure that folds from A4 into A5, your artwork must account for the fold and bleed areas. Guessing costs you time or prints.
How to Choose the Right Paper Size
Ask these questions:
- Where will this be printed? (US market = Letter; international = A4)
- What will hold the paper? (envelopes, binders, frames have fixed dimensions)
- What content goes on it? (amount of text, images, folding requirements)
- What's the standard in your industry? (legal docs = Legal in US; contracts often still = Letter)
If you're designing for unknown print locations, A4 or Letter are your safest bets. They fit standard office equipment worldwide.
Quick Conversion Reference
| US Size | Closest ISO Equivalent | Difference |
|---|---|---|
| Letter (8.5×11") | A4 (8.3×11.7") | Letter is wider but shorter |
| Legal (8.5×14") | No direct equivalent | Longer than A4; similar width |
| Tabloid (11×17") | A3 (11.7×16.5") | Close but not identical |
Getting Started: Setting Up Your Documents
In design software:
- Adobe InDesign/Illustrator: Create new document → select page size from presets or enter custom dimensions
- Microsoft Word: Layout → Size → select from list or enter custom (check "Paper" tab in older versions)
- Canva: Custom dimensions option when starting a design
Always set your document size to the final trimmed size. Add bleed separately if needed (usually 3mm or 0.125 inches beyond the trim).
The Bottom Line
Paper sizes aren't complicated, but the differences between systems trip people up constantly. Know your market. If you're in the US, use Letter. If you're outside North America, use A4. If you're doing international work, design in A4 and adjust for Letter when needed.
Keep this guide handy. You'll reference it more than you expect.