Convert Paper Size
Convert paper size measurements between different units quickly and accurately
Paper Size Conversion Calculator
Popular Paper Size Conversions
Quickly convert between the most commonly used paper sizes.
Understanding Paper Size Standards
Paper size conversions are essential for printing, publishing, and international business. Different regions use various paper size standards (A-series, US Letter, Legal, etc.), and understanding these conversions is crucial for document formatting, printing, and office work.
Common Paper Size Standards
ISO (A/B/C Series)
- A0-A6 - International standard sizes
- B4, B5 - Intermediate sizes
- C4, C5 - Envelope sizes for A-series papers
US/Canada Sizes
- Letter (8.5 × 11 in) - Standard US size
- Legal (8.5 × 14 in) - Legal documents
- Tabloid (11 × 17 in) - Posters, large prints
- Executive (7.25 × 10.5 in) - Memos, notepads
Common Applications
| Field | Paper Types | Typical Uses |
|---|---|---|
| Business | A4, Letter | Reports, letters, contracts |
| Publishing | A5, B5, Executive | Books, booklets, notepads |
| Posters | A3, Tabloid | Large prints, marketing |
| Mailing | C4, C5 | Envelopes for A4/A5 documents |
Conversion Tips
- A4 is slightly taller and narrower than US Letter
- 1 inch = 25.4 millimeters for size conversions
- ISO sizes halve in area from one size to the next (A3 = 2 × A4)
- Always check printer compatibility for non-standard sizes
Paper Size Conversions
| Conversion | Formula | Quick Answer |
|---|---|---|
| A4 to Letter | A4 (210 × 297 mm) ≈ Letter (216 × 279 mm) | A4 is taller, Letter is wider |
| Letter to A4 | Letter (8.5 × 11 in) ≈ A4 (8.27 × 11.69 in) | Letter is shorter, A4 is narrower |
| A3 to Tabloid | A3 (297 × 420 mm) ≈ Tabloid (279 × 432 mm) | A3 is slightly narrower and shorter |
| Tabloid to A3 | Tabloid (11 × 17 in) ≈ A3 (11.7 × 16.5 in) | Tabloid is wider, A3 is taller |
| A5 to Executive | A5 (148 × 210 mm) ≈ Executive (184 × 267 mm) | Executive is larger |
| C4 to A4 | C4 envelope fits A4 paper unfolded | C4 = 229 × 324 mm |
| C5 to A5 | C5 envelope fits A5 paper unfolded | C5 = 162 × 229 mm |
| B5 to A5 | B5 (176 × 250 mm) is larger than A5 (148 × 210 mm) | B5 is for books, A5 for booklets |
| Legal to A4 | Legal (8.5 × 14 in) ≈ A4 (8.27 × 11.69 in) | Legal is longer |
| A4 to Legal | A4 (210 × 297 mm) ≈ Legal (216 × 356 mm) | Legal is longer |
Our paper size conversion tool provides accurate conversions between all major international and US paper sizes, making it easy to format documents, print, and mail worldwide. Whether you're working in business, publishing, or design, our converter ensures precise paper size conversions for any application.
Paper Size Conversion Questions
Everything you need to know about paper size standards and conversions
What's the difference between A4 and Letter size?
A4 (210 × 297 mm) is slightly taller and narrower than US Letter (8.5 × 11 in or 216 × 279 mm). A4 is part of the ISO standard used worldwide, while Letter is the standard in the US and Canada. A4 has a consistent aspect ratio that allows easy scaling.
Why does the world use different paper standards?
Paper standards developed regionally before global standardization. The ISO A-series was designed with mathematical precision (each size is exactly half the area of the next), while US sizes evolved from practical printing needs. The US continues to use its traditional sizes despite global ISO adoption.
Can I print A4 documents on Letter-size paper?
Yes, but with some adjustments. A4 is taller than Letter, so content may be cut off or scaled down. Most printers offer 'fit to page' or 'scale to fit' options. For best results, design documents specifically for your target paper size.
What are B and C series paper sizes used for?
B-series sizes are intermediate sizes (larger than A but smaller than the next A size) often used for books, posters, and magazines. C-series sizes are designed for envelopes - C4 fits A4 unfolded, C5 fits A5 unfolded, etc.
How do I choose the right envelope size for my document?
For unfolded documents, use C-series envelopes (C4 for A4, C5 for A5). For folded documents, you can use smaller envelopes. Always check that your printer can handle the envelope size and that postal services accept it.
Are there paper sizes smaller than A6 or larger than A0?
Yes! The A-series extends both ways: A7, A8, A9, A10 get progressively smaller, while A0 can be extended to larger formats. However, A6 to A0 covers most practical needs. Very large formats are often custom-made for specific applications.
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