Overshoot (typography)

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, or to which a lowercase letter goes below the baseline or above the x-height.

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.