Acceleration Units

Acceleration is a physical quantity that shows how much the speed of a body changes as it moves over a unit of time.

International System of Units (SI)

The unit of acceleration in the International System of Units (SI) is the meter per second per second [m / s²].
  Derivatives from speed and time can also be used:

• 1 Kilometer per second² [km/s²] = 1000 m/s²
• 1 Meter per second² [m/s²] = 1000 mm/s²

Imperial and Customary units

Since in some English-speaking countries the distance units are miles, feet and inches, we get:

• 1 Miles per second² [mps²] = 1.609,344 km/s²
• 1 foot per second² [fps²] = 0.304 m/s²
• 1 inch per second² [ips²] = 25.4 mm/s²