Fitts's law: why the menu bar is at the top

This explains why the persistent menu bar sits at the top of the screen by applying Fitts's law, the 1954 model that predicts pointing time as T = a + b·log2(1 + D/W). Only the ratio of distance (D) to target size (W) matters, and because the screen edge prevents the pointer from leaving, the effective width of a top-of-screen menu becomes effectively infinite. That makes the menu bar dramatically faster to hit than a thin, in-window menu that requires aiming and stopping. Corners, where two edges meet, are even easier targets, which is why designers use them for quick shortcuts and why early Windows mistakes (an unresponsive Start-button border) and later fixes adopted edge-aligned hit areas.

The piece also covers the tradeoffs: window-attached menus avoid having to activate an app first and can be better on large or multi-display setups (macOS later added per-display bars), while web apps rarely touch screen edges and must rely on larger targets, accessible hit-area rules (WCAG’s 24×24px guidance), and context menus that appear under the pointer to minimize D. Newer platforms with pointers, like iPadOS, still put menus at the top. The position is thus a practical consequence of how pointing works rather than stylistic preference: the pointer can’t miss an edge-aligned bar.