ISBN barcode size has strict requirements on size. According to [https://www.bisg.org/barcoding-guidelines-for-the-us-book-industry](Barcoding Guidelines for the U.S. Book Industry):
The Bookland EAN symbol is printed on Cover 4 (the back cover) of all books and on Cover 2 (inside front cover) of strippable paperbacks. The symbol, which may includes the 5-digit price extension, is 1" high x 2-3/16" wide at 100% magnification. At 80% magnification the overall size is approximately 13/16" high x 1-3/4" wide. Magnification may be any size between 80% and 200%. With offset printing it should not be necessary to print larger than 100%. Width is measured with a 3/32 inch "quiet zone" on either side of bars. Height is measured from the top of the bars to the bottom of the numbers below the bars.
It can be anywhere from 80% to 200%. But what is 100%?
From experimenting in Inkscape, it seems that a font size of 80pt is very close to 100%, only slightly larger, according to European recommendations in mm.
If indeed it is 80pt, then I think users would benefit from having that number, plus the 80-200% range numbers mentioned in the documentation, to ensure they have the right size.
ISBN barcode size has strict requirements on size. According to [https://www.bisg.org/barcoding-guidelines-for-the-us-book-industry](Barcoding Guidelines for the U.S. Book Industry):
It can be anywhere from 80% to 200%. But what is 100%?
From experimenting in Inkscape, it seems that a font size of 80pt is very close to 100%, only slightly larger, according to European recommendations in mm.
If indeed it is 80pt, then I think users would benefit from having that number, plus the 80-200% range numbers mentioned in the documentation, to ensure they have the right size.