The average raindrop falls at about 21 feet per second. That figure describes a typical drop’s falling speed through still air, not a universal speed for every drop in every storm.
Raindrops accelerate because gravity pulls them downward, but air resistance eventually balances that force. The drop then reaches terminal velocity. Its size and shape matter: tiny drops fall slowly, while larger drops can descend much faster before air pressure flattens or breaks them apart.
A typical raindrop is only about 1 to 2 millimeters across. Large drops may approach roughly 30 feet per second, while drizzle-sized droplets can fall far more slowly. Wind can also change the drop’s path and its speed relative to the ground.
The familiar 21-feet-per-second answer is therefore a useful average for general-interest trivia. It should not be confused with the speed of water running down a window or with the much faster motion a drop would have in a vacuum, where air resistance would be absent.