Convert Mile/Hour (mi/h) to Millimeter/Hour (mm/h) instantly.
About these units
Mile/Hour (mi/h)
The mile per hour represents the number of miles traveled in one hour and is commonly used in the United States, the UK (in road contexts), and several other countries with legacy imperial systems. mph is deeply woven into cultural habits: driver training, speed limits, vehicular performance, and even athletic achievements are often expressed in miles per hour. In science and engineering, however, mph is rarely used because the mile and hour are not SI units. Still, mph retains strong emotional and historical associations—for example, the significance of a car "breaking 200 mph" or the legendary "88 mph" in popular culture. It persists because measurement units often survive long after their historical origins fade.
Millimeter/Hour (mm/h)
A millimeter per hour is extraordinarily slow, used in geology, meteorology, and materials science to measure phenomena like soil creep, tectonic plate micro-motion, or extremely light precipitation (drizzle). In manufacturing, mm/h may describe slow deposition rates in thin-film fabrication or high-precision milling processes. Despite seeming negligible, speeds measured in mm/h can accumulate into significant changes over weeks, months, or years—making them essential for long-term studies.