The Leonardo da Vinci device designed to record the distance traveled by a wheeled vehicle was an odometer.
Leonardo drew a cart-like measuring device in the Codex Atlanticus. As its wheel turned, gears transferred motion to a mechanism that counted rotations. Each completed rotation represented a known distance based on the wheel’s circumference, allowing the device to record how far the vehicle had traveled.
The design belongs to a long history of mechanical distance measurement. Ancient Roman surveyors used related instruments, and modern odometers are standard features in cars, bicycles, and other vehicles. Leonardo’s version was especially valuable as a surveying and road-measurement concept.
An odometer measures accumulated distance, while a speedometer measures current speed. The two instruments can work together but answer different questions. Leonardo’s drawing is commonly cited as an early vehicle odometer concept, not as evidence that every Renaissance cart carried one.