## B10 size is the smallest B paper size standardized. It was standardized by ISO 216 in 1975, even if the formats B were first published by DIN (*German Institute for Standards*) in 1922.

This was a result of ratio Lichtenberg, who explained it in 1786 in a letter that was written on a sheet that met the √2 ratio.

Since then, the proportions between the B formats are always kept between two sizes: √2 (a / b = 2b / a = 1.4142). This implies to enlarge B10 to larger B sizes without changing its content.

Format B10 measures half a B9 size, ¼ a B8, ⅛ a B7.... Its area is 0.0014 m² (or 0.01 square foot, 1.5 square inches). Its length is equal to a B9 width.

B10 format is quite little used, and almost never at home or business. Like all B formats, it is primarily used by professional printers, which create small cards or coupons from it.

To calculate weight, its area must be multiplied by the weight of the chosen paper, which is always expressed in g/m². For example, for a paper of 160 g/m², we have the following calculation: 0.0014 x 160 = 0.224 grams per B10 sheet.