Convert acceleration between m/s², standard gravity, ft/s², Gal, and speed gained per second. Negative acceleration values are supported, so a signed change in velocity keeps its sign.
How to use this calculator
Choose the original acceleration unit and the desired unit, then enter your value. If a measurement says miles per hour gained each second, select mph/s. If it only says mph, that is a speed and cannot be converted to acceleration without a time interval.
Why the second time unit matters
Acceleration measures how quickly velocity changes. Meters per second squared means a change of one meter per second during each second. It is not the same as meters per second.
The standard-gravity option uses g₀ = 9.80665 m/s². Local gravitational acceleration varies with position; this fixed reference is useful for expressing accelerometer readings and engineering quantities. A Gal is one centimeter per second squared. Milli-g means one thousandth of standard gravity, not a milligram of mass.
Examples
One standard gravity
1 g₀ = 9.80665 m/s², or approximately 32.17404856 ft/s².
A slowing vehicle
A change of −10 mph over 2 seconds is −5 mph/s. Converting this acceleration gives −2.2352 m/s². This is an average over the interval, not an instantaneous measurement.
Formula
acceleration = change in velocity / elapsed time
1 g₀ = 9.80665 m/s²
1 mph/s = 0.44704 m/s²
1 km/h/s = (1 / 3.6) m/s²
Precision and interpretation
These are unit conversions, not a model of a vehicle or a person under acceleration. A negative number indicates direction relative to a selected axis; it does not always mean an object is slowing down. Results use floating-point arithmetic and up to 12 significant digits.
Definitions and further reading
Unit and quantity reference provides the underlying definitions. The examples above are worked calculations for this tool.