A-Series Paper Size Calculator
Select an A-series paper size to see its dimensions in millimeters, centimeters, and inches, plus area, perimeter, diagonal, and sheet relationships.
Last updated: July 2026
Paper dimensions
A-series relationship
A0–A10 reference table
| Size | Millimeters | Centimeters | Inches |
|---|---|---|---|
| A0 | 841 × 1189 mm | 84.1 × 118.9 cm | 33.1102 × 46.8110 in |
| A1 | 594 × 841 mm | 59.4 × 84.1 cm | 23.3858 × 33.1102 in |
| A2 | 420 × 594 mm | 42 × 59.4 cm | 16.5354 × 23.3858 in |
| A3 | 297 × 420 mm | 29.7 × 42 cm | 11.6929 × 16.5354 in |
| A4 | 210 × 297 mm | 21 × 29.7 cm | 8.2677 × 11.6929 in |
| A5 | 148 × 210 mm | 14.8 × 21 cm | 5.8268 × 8.2677 in |
| A6 | 105 × 148 mm | 10.5 × 14.8 cm | 4.1339 × 5.8268 in |
| A7 | 74 × 105 mm | 7.4 × 10.5 cm | 2.9134 × 4.1339 in |
| A8 | 52 × 74 mm | 5.2 × 7.4 cm | 2.0472 × 2.9134 in |
| A9 | 37 × 52 mm | 3.7 × 5.2 cm | 1.4567 × 2.0472 in |
| A10 | 26 × 37 mm | 2.6 × 3.7 cm | 1.0236 × 1.4567 in |
What this A-series paper calculator tells you
Select A0 through A10 to see fixed standard dimensions in millimeters and conversions to centimeters and inches. The calculator also reports single-sheet geometry, combined face area for a quantity, and nominal A-series relationships.
A0 through A10 paper dimensions
The reference table uses the published whole-millimeter dimensions for every supported size. These fixed values avoid cumulative errors that could arise from repeatedly halving and rounding a previous size.
How A-series paper sizes are related
Nominally, cutting a sheet in half parallel to its shorter side creates two sheets of the next smaller size while preserving approximately the same proportions. A size An corresponds to 2n nominal sheets per A0 and n successive halvings.
Portrait versus landscape orientation
Portrait places the shorter standard side first as width; landscape swaps width and height. Orientation does not change area, perimeter, diagonal, quantity totals, or parent and child relationships.
How area, perimeter, and diagonal are calculated
Area is width multiplied by height, perimeter is twice the sum of width and height, and diagonal uses the Pythagorean relationship through Math.hypot. Quantity multiplies only one-face sheet area—not dimensions, perimeter, diagonal, or double-sided surface area.
Why A-series measurements are slightly rounded
The theoretical A-series aspect ratio is √2:1 and A0 has a nominal area of one square meter. Published dimensions are rounded to whole millimeters, so ratios and areas calculated from them differ slightly. For example, 841 × 1,189 mm gives 999,949 mm².
Worked examples
A4 portrait
A4 is 210 × 297 mm, 21 × 29.7 cm, or approximately 8.2677165 × 11.6929134 inches. Its area is 62,370 mm², perimeter is 1,014 mm, and diagonal is approximately 363.7430412 mm. It is four halvings from A0, with 16 nominal sheets per A0, parent A3, and child A5.
Ten A3 landscape sheets
A3 landscape is 420 × 297 mm. Each sheet has an area of 124,740 mm², so ten sheets have 1,247,400 mm² or 1.2474 m² of combined face area. Perimeter is 1,434 mm, diagonal is approximately 514.4015941 mm, and there are eight nominal A3 sheets per A0.
A0 portrait
A0 is 841 × 1,189 mm. The rounded dimensions produce 999,949 mm² or 0.999949 m². It has zero halvings, one nominal sheet per A0, no supported parent, and child A1.
One hundred A5 sheets
A5 is 148 × 210 mm, with 31,080 mm² per sheet. One hundred sheets have 3,108,000 mm² or 3.108 m² of combined face area. A5 has parent A4, child A6, and 32 nominal sheets per A0.
Frequently asked questions
What size is A4 paper?
A4 is 210 × 297 mm in portrait orientation.
What are A4 dimensions in inches?
Approximately 8.2677 × 11.6929 inches.
What size is A3 paper?
A3 is 297 × 420 mm in portrait orientation.
Is A4 half of A3?
Nominally, one A3 corresponds to two A4 sheets. Physical areas from rounded millimeter dimensions can differ slightly.
How many A4 sheets fit into one A0 sheet?
The nominal relationship is 16 A4 sheets per A0.
Why is A0 not exactly one square meter using rounded dimensions?
The published 841 × 1,189 mm dimensions are rounded to whole millimeters and produce 0.999949 m².
Does landscape paper have a different area?
No. Landscape only swaps width and height.
What is the aspect ratio of A-series paper?
The theoretical ratio is √2:1. Rounded whole-millimeter sizes only approximate it.
Is A4 the same as US Letter?
No. They have different dimensions and proportions.
Does this calculator include printer margins?
No. Printable area depends on the printer and settings.
Can I calculate pixels or DPI for an A-size print?
Pixel requirements depend on DPI and are outside this calculator. Use the related Image Print Size Checker.
Can I calculate the weight of multiple sheets?
Not here. Paper weight requires the paper's GSM as well as area.
Are A-series dimensions identical in every country?
ISO A-series dimensions are standardized, but users should confirm accepted sizes with a printer, print shop, carrier, or document requirement when exact compliance matters.