Paper size chart.
ISO 216 A & B series (international standard) and ANSI US Letter family. Plus bleed margins, safe-area conventions, and the math behind why A4 has the proportions it does.
ISO 216 A series
Each size has an aspect ratio of 1 : √2 (≈ 1.414) — so cutting any A-size in half across the long edge gives two of the next size down.
A0 is defined as 1 m² of area. The "international standard" used by ~96% of the world.
| Size | Dimensions (mm) | Dimensions (inch) | Area |
|---|---|---|---|
| 4A0 | 1682 × 2378 mm | 66.22 × 93.62" | 4.000 m² |
| 2A0 | 1189 × 1682 mm | 46.81 × 66.22" | 2.000 m² |
| A0 | 841 × 1189 mm | 33.11 × 46.81" | 1.000 m² |
| A1 | 594 × 841 mm | 23.39 × 33.11" | 0.500 m² |
| A2 | 420 × 594 mm | 16.54 × 23.39" | 0.249 m² |
| A3 | 297 × 420 mm | 11.69 × 16.54" | 0.125 m² |
| A4 | 210 × 297 mm | 8.27 × 11.69" | 0.062 m² |
| A5 | 148 × 210 mm | 5.83 × 8.27" | 0.031 m² |
| A6 | 105 × 148 mm | 4.13 × 5.83" | 0.016 m² |
| A7 | 74 × 105 mm | 2.91 × 4.13" | 0.008 m² |
| A8 | 52 × 74 mm | 2.05 × 2.91" | 0.004 m² |
| A9 | 37 × 52 mm | 1.46 × 2.05" | 0.002 m² |
| A10 | 26 × 37 mm | 1.02 × 1.46" | 962 mm² |
ISO 216 B series
B sizes are geometric means of adjacent A sizes — used for posters, books, envelopes, and any time you need a size that falls between two A sizes.
| Size | Dimensions (mm) | Dimensions (inch) |
|---|---|---|
| B0 | 1000 × 1414 mm | 39.37 × 55.67" |
| B1 | 707 × 1000 mm | 27.83 × 39.37" |
| B2 | 500 × 707 mm | 19.69 × 27.83" |
| B3 | 353 × 500 mm | 13.90 × 19.69" |
| B4 | 250 × 353 mm | 9.84 × 13.90" |
| B5 | 176 × 250 mm | 6.93 × 9.84" |
| B6 | 125 × 176 mm | 4.92 × 6.93" |
| B7 | 88 × 125 mm | 3.46 × 4.92" |
| B8 | 62 × 88 mm | 2.44 × 3.46" |
US / ANSI series
The US system originated separately from ISO 216 and uses 8.5″ × 11″ as the standard (ANSI A). Each ANSI size doubles by halving (like the A series), but the aspect ratio alternates between 1.294 and 1.545, so the sizes aren't geometrically similar to each other.
| Size | Inches | Millimeters |
|---|---|---|
| Letter / ANSI A | 8.5 × 11" | 216 × 279 mm |
| Legal | 8.5 × 14" | 216 × 356 mm |
| Tabloid / ANSI B | 11 × 17" | 279 × 432 mm |
| ANSI C | 17 × 22" | 432 × 559 mm |
| ANSI D | 22 × 34" | 559 × 864 mm |
| ANSI E | 34 × 44" | 864 × 1118 mm |
| Half Letter | 5.5 × 8.5" | 140 × 216 mm |
| Junior Legal | 5 × 8" | 127 × 203 mm |
| Government Letter | 8 × 10.5" | 203 × 267 mm |
Bleed and safe area for print design
When you design something to be printed and trimmed, the actual cut isn't perfectly precise — typical commercial cutting tolerance is ±1–2 mm. To avoid an unprinted edge after trimming, you extend the design past the trim line by the bleed amount, then trim back to the final size.
| Standard | Bleed | Safe area inset | When to use |
|---|---|---|---|
| Digital print (short run) | 3 mm (1/8") | 3 mm | Standard for digital business cards, flyers, brochures. |
| Offset print (commercial) | 3 mm (1/8") | 3-5 mm | Standard for commercial offset. |
| Large format / poster | 5-10 mm | 10 mm | Bigger sizes = more cutting tolerance needed. |
| Book covers / wrap | 10-15 mm | 5-10 mm from spine | Wrap and spine variations need bigger bleed. |
| Packaging / die-cut | 3 mm | 3-5 mm from die line | Die-cutting tolerance similar to trim. |
| US trade ("full bleed") | 1/8" (3.175 mm) | 1/8" | US shops often spec in inches; same idea. |
Common pitfalls
- A4 ≠ Letter. A4 (210 × 297 mm) is narrower and taller than US Letter (216 × 279 mm). A document designed for one won't fit cleanly on the other. Use "scale to fit" carefully — text can become unreadably small or oversized.
- Forgetting bleed crashes designs at the print shop. If your background extends to the edge of the trim line (with no bleed), the trim tolerance shows as a white sliver. Always extend bleed by 3 mm minimum.
- Safe area protects critical content. Text or logos near the edge get clipped if the trim is off. Keep ≥ 3 mm (better: 5 mm) inside the trim for text.
- "Letter size paper" varies by country. In the US/Canada/Mexico, it's 8.5 × 11. In Latin America, "carta" is also 8.5 × 11. Most of the world: A4.
- Envelope sizes don't follow paper sizes. #10 (US business envelope) and DL (European business envelope) are different. C4 envelopes fit unfolded A4; DL envelopes fit A4 folded in thirds.
Common questions
Why is A4 the size it is?
A4 is based on the ISO 216 √2 ratio: when folded in half lengthwise, you get A5 with the same proportions. The full sheet A0 is exactly 1 m² of area; each smaller size halves that area while keeping the aspect ratio. So A4 = 1/16 m² = 210 × 297 mm. The √2 ratio makes scaling between sizes mathematically clean.
Is US Letter the same as A4?
Close, but not the same. US Letter is 8.5 × 11 in (216 × 279 mm); A4 is 210 × 297 mm. A4 is taller and slightly narrower. Documents designed for one don't always fit the other — a margin-tight A4 PDF may have content cut off when printed on US Letter, and vice versa.
What's the largest standard paper size?
In the A series, A0 = 841 × 1189 mm (about 33.1 × 46.8 in) — roughly poster size. Above that, ISO defines 2A0 and 4A0 for special applications. In US sizes, the largest common is Bond E (34 × 44 in) used for architectural and engineering drawings.
How do I figure out what envelope to use for an A4 letter?
DL envelope (110 × 220 mm) holds A4 folded in three. C5 envelope (162 × 229 mm) holds A4 folded in half. C4 envelope (229 × 324 mm) holds A4 unfolded. The C-series and DL are sized specifically to match the A-series; never mix US #10 (104 × 241 mm) with A4 — it's a slightly different fold.
What's the deal with 'B' paper sizes?
ISO B-series sizes sit between A-series sizes — B5 is bigger than A5 but smaller than A4. They're used for books, posters, and passports (B7). The dimensions are the geometric mean of adjacent A sizes. B-series is less common in office use but very common for books and special print products.
Sources
- A and B series: ISO 216:2007 — Writing paper and certain classes of printed matter — Trimmed sizes — A and B series.
- C series envelopes: ISO 269 (now part of ISO 216).
- US sizes: ANSI/ASME Y14.1 — Decimal Inch Drawing Sheet Size and Format.
- Bleed conventions: Vary by printer; the values above are widely-accepted industry standards.
Disclaimer. Always confirm bleed and safe-area requirements with your specific print provider, especially for non-standard formats, packaging, or large-format work.