Hello Typophiles:
Just wondering if anyone knows the history of any proposals that may have been made in the past to systematize a universal "x-factor" for typefaces that would allow easy calculation of ideal body text sizing? (Searching the forums didn't reveal any hits...)
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For example:
If we just hypothetically used Helvetica 55 as the universal standard yardstick (since it's so ubiquitous), we could give this font an "x-factor" of 1.000 and then assign an x-factor to all other fonts based on the ratio of their x-heights to Helvetica's (using 1000 UPM measurements).
Helvetica:
714 (ascend) + 286 (descend) = 1000 UPM
517 = x-height
Times New Roman:
717 (ascend) + 283 (descend) = 1000 UPM
461 = x-height
So, the "x-factor" of Times New Roman compared to Helvetica would be:
517 / 461 = 1.122.
Therefore, if you regularly set Helvetica at 10 points, then you would set Times at 11.25:
10 * 1.122 = 11.25 (rounded to nearest 1/4 point)
If this x-factor number were published with fonts, it might make it easier to help non-techie and non-designer font users make better sizing choices instead of resorting to naming solutions like "Baskerville 10" to show intent at 10-point size...