To find the paper sizes for A, B, and C sheets of the ISO standard, read on!

### What is ISO Paper anyway?

ISO (International Organisation for Standardisation) 216 paper sizes are based on an aspect ratio of approximately 1:1.4142 – the square root of 2. The base format (A0) is a sheet spanning 1m² in area. Successive sheets in the series are made by halving the preceding paper size along the larger edge.

The advantage of this system lies in scaling: if a sheet with an aspect ratio of √2 is divided into two equal halves parallel to its shortest sides, then the halves will again have an aspect ratio of √2.

Developed from earlier ideas in Germany in 1922, the system quickly spread to other countries, and was established as an ISO standard in 1975.

### A Series

The most frequently used of this series is A4. The US ‘Letter’ paper size – that you may frequently select by mistake in MS Word (as I do) – is 6mm wider and 18mm shorter than this.

Sheet | Dimensions (mm) |
---|---|

A0 | 1189 x 841 |

A1 | 841 x 594 |

A2 | 594 x 420 |

A3 | 420 x 297 |

A4 | 297 x 210 |

A5 | 210 x 148 |

A6 | 148 x 105 |

A7 | 105 x 74 |

A8 | 74 x 52 |

A9 | 52 x 37 |

A10 | 37 x 26 |

### B Series

In less common use, the B Series is the geometric mean of successive A sheets. B sizes are usually found in poster design, books and envelopes.

Sheet | Dimensions (mm) |
---|---|

B0 | 1414 x 1000 |

B1 | 1000 x 707 |

B2 | 707 x 500 |

B3 | 500 x 353 |

B4 | 353 x 250 |

B5 | 250 x 176 |

B6 | 176 x 125 |

B7 | 125 x 88 |

B8 | 88 x 62 |

B9 | 62 x 44 |

B10 | 44 x 31 |

### C Series

The C series is used only for envelopes. The area of C series sheets is the geometric mean of the areas of the A and B series sheets of the same number.

Sheet | Dimensions (mm) |
---|---|

C0 | 1297 x 917 |

C1 | 917 x 648 |

C2 | 648 x 458 |

C3 | 458 x 324 |

C4 | 324 x 229 |

C5 | 229 x 162 |

C6 | 162 x 114 |

C7 | 114 x 81 |

C8 | 81 x 57 |

C9 | 57 x 40 |

C10 | 40 x 28 |