Ad space in Japanese newspapers is measured principally in "dan" (horizontal columns), with the following features: 

ex. Full page = 15 columns, half page = 7 columns, 1/3 page = 5 columns, quarter page = 7 1/2 columns

• One column of advertising is about 32 mm deep x 382 mm wide in terms of article layout. 
• A full-page ad consists of 15 columns (514 mm deep x 382 mm wide).
• Typical display ad spaces in Japanese newspapers are 15, 10, 7, 5, 3, 5 x 1/2, 2, and 2 x 1/2 columns.

With minor exceptions, all ad space in Japanese newspapers is measured in terms of columns.