441. The Size of Various Measurements

Tefillin, Mezuzah v’Sefer Torah 9:8

If one wants to make the width of a sefer Torah more than six or less than six thumb-widths, he makes similar calculations. As long as one does not make a mathematical error, the length of the Torah will equal its circumference.

Tefillin, Mezuzah v’Sefer Torah 9:9

The thumb-width mentioned throughout is the width of the average person's thumb. This is equal to the width of seven average barleycorns when placed tightly next to one another, or the length of two barleycorns spaced apart. A handbreadth is four thumb-widths. A cubit is six handbreadths.