In typeface design, the overshoot of a round or pointed letter (like O or A) is the degree to which it extends higher or lower than a comparably sized "flat" letter (like X or H), to achieve an optical effect of being the same size; it compensates for inaccuracies in human visual perception. Formally, overshoot is the degree to which capital letters go below the baseline or above the

cap height In typography, cap height is the height of a capital letter above the baseline for a particular typeface A typeface (or font family) is a design of Letter (alphabet), letters, Numerical digit, numbers and other symbols, to be used in printing ...

, or to which a lowercase letter goes below the baseline or above the

x-height upright 2.0, alt=A diagram showing the line terms used in typography In typography, the x-height, or corpus size, is the distance between the baseline and the mean line of lowercase letters in a typeface. Typically, this is the height of the le ...

. For example, the highest and lowest extent of the capital O will typically exceed those of the capital X. Although the extent of overshoot varies depending on the design and the designer, perhaps 1% to 3% of the cap or x-height is typical for O. Peter Karow's ''Digital Formats for Typefaces'' recommends 3% for O and 5% for A.

Similar design

Similar subtle adjustments to create an even appearance occur in other fields. For example, in the game of go, the

stones In geology, rock (or stone) is any naturally occurring solid mass or aggregate of minerals or mineraloid matter. It is categorized by the minerals included, its Chemical compound, chemical composition, and the way in which it is formed. Rocks ...

, which are black and white, are of slightly different sizes (black slightly larger), to give the appearance of being the same size.

References

{{Typography terms Typography