# The basics of paper

## Paper grain

The direction of the paper fibers is easy to arrange with machines, and the strength of the paper varies depending on that direction. The direction in which the paper machine runs is the paper’s vertical height. In a right angle to this direction is the paper’s horizontal height. The direction in which the fibers are arranged in is called “grain”. Paper grain can be very important depending on the purpose of the paper, and most paper products are printed and processed while paying close attention to the “grain.”

The way to determine paper grain is to tear up the paper. If it produces a “clean cut”, then the direction is vertical; if the cut makes jagged pieces, then the direction is horizontal.

## Paper density and paper quantity

Paper density is the weight of paper in grams per square meter. The unit is g/m². By using this unit you can roughly understand the properties of the paper such as its strength and thickness.

Paper quantity refers to the weight of 1 paper bundle. The unit is kg. The weight of 1 bundle equals the weight of 1000 printing paper sheets or 100 cardboards.

〈Calculation method for paper quantity〉

Printing paper quantity = Paper density (g/m²) x area （㎡）x 1000 (sheets)

Cardboard quantity = Paper density (g/m²) x area（㎡）x 1000 (sheets)

## Dimensions

It refers to the size of the paper which is expressed as horizontal (width) x vertical (length). In JIS (Japanese Industrial Standards), there are “trimmed size” and the “untrimmed size” dimensions.

〈Trimmed size〉Number | A column (mm) | B column (mm) |
---|---|---|

0 | 841×1189 | 1030×1456 |

1 | 594×841 | 728×1030 |

2 | 420×594 | 515×728 |

3 | 297×420 | 364×515 |

4 | 210×297 | 257×364 |

5 | 148×210 | 182×257 |

6 | 105×148 | 128×182 |

7 | 74×105 | 91×128 |

8 | 52×74 | 64×91 |

9 | 37×52 | 45×64 |

10 | 26×37 | 32×45 |

11 | 18×26 | 22×32 |

12 | 13×18 | 16×22 |

* All dimensions are in long grain.

〈Untrimmed printing paper〉Title | Dimension (mm) | Area（㎡） |
---|---|---|

Duodecimo | 788×1091 | 0.860 |

B size | 765×1085 | 0.830 |

A size | 625×880 | 0.555 |

A5 | 636×939 | 0.597 |

Patron size | 900×1200 | 1.080 |

* All dimensions are in long grain.

〈Untrimmed paper board〉Title | Dimension (mm) | Area（㎡） |
---|---|---|

K size | 65×95 | 0.175 |

L size | 80×110 | 1.080 |

* All dimensions are in long grain.