Acceleration is how quickly velocity changes. Physicists write it in meters per second squared, American engineers often use feet per second squared, pilots and roller-coaster designers speak in g, and geophysicists measure minute gravity changes in milligals. Car magazines skip the units altogether and quote 0–60 times. This converter moves between all of these, and for any acceleration it also tells you how long a steady push would take to reach 60 mph and 100 km/h.
How to use the acceleration converter
- Enter the acceleration in Value.
- Choose its unit in From and the unit you want in To.
- The tape shows the converted value, both conversion factors and the 0–60 mph and 0–100 km/h times at that constant acceleration.
- The table gives the value in every supported unit.
Acceleration conversion formula
Each unit is defined by how many meters per second squared it represents:
The anchor values are exact: 1 g = 9.80665 m/s², 1 ft/s² = 0.3048 m/s², 1 Gal = 0.01 m/s², and 1 mph per second = 0.44704 m/s². To get a 0–60 time from an acceleration, divide the speed by the acceleration:
Worked example: a 2.5 g launch
A launched roller coaster advertises an acceleration of 2.5 g. In SI units:
2.5 g × 9.80665 = 24.516625 m/s²
In ft/s²: 24.516625 ÷ 0.3048 = 80.44 ft/s².
Time to reach 60 mph: 26.8224 ÷ 24.516625 ≈ 1.09 s.
That 1.09-second figure assumes the acceleration stays constant, which is close to true for a magnetic launch and far from true for a car whose grip and power change with speed.
Common acceleration conversions
| From | To | Multiply by |
|---|---|---|
| g (standard gravity) | m/s² | 9.80665 (exact) |
| m/s² | g | 0.1019716 |
| g | ft/s² | 32.174049 |
| ft/s² | m/s² | 0.3048 (exact) |
| m/s² | ft/s² | 3.2808399 |
| Gal (cm/s²) | m/s² | 0.01 (exact) |
| mph per second | m/s² | 0.44704 (exact) |
| km/h per second | m/s² | 0.2777778 |
Acceleration in everyday terms
| Situation | Approximate acceleration |
|---|---|
| Gravity on the Moon | 1.62 m/s² (0.17 g) |
| Typical family car, 0–60 mph in 9 s | 3.0 m/s² (0.30 g) |
| Hard braking on dry pavement | 7–9 m/s² (0.7–0.9 g) |
| Free fall near Earth’s surface | 9.81 m/s² (1 g) |
| Space shuttle at main-engine cutoff | about 29 m/s² (3 g) |
| Fighter pilot in a tight turn | up to 88 m/s² (9 g) |
Things to keep in mind
Standard gravity is a convention. The value 9.80665 m/s² was chosen as a reference and is used to define units such as the kilogram-force and the pound-force. Actual gravity at your location differs slightly with latitude and altitude, which matters for precise scales but not for most conversions.
“g” is not “gram.” In acceleration, a lowercase g means standard gravity. The context and the unit list here keep them apart, but be careful when reading spreadsheets or sensor data, where “g” might mean either.
Accelerometer readings include gravity. A phone lying still on a table reports about 1 g upward because the sensor measures the table pushing back against gravity. Subtract 1 g along the vertical axis when you want motion alone.
To work through motion problems with acceleration, time and distance, use the uniformly accelerated motion calculator or the simpler acceleration calculator. The force converter shows how the kilogram-force and pound-force are built from standard gravity.
Frequently asked questions
How many m/s² is 1 g?
Exactly 9.80665 m/s². That value is standard gravity, a conventional figure adopted in 1901 by the General Conference on Weights and Measures. Real gravity varies from about 9.78 m/s² at the equator to 9.83 m/s² at the poles.
How do I convert m/s² to ft/s²?
Divide by 0.3048, or multiply by about 3.28084. Standard gravity is 9.80665 m/s², which equals 32.174 ft/s².
What does a 0–60 time tell me about acceleration?
Sixty mph is 26.8224 m/s, so the average acceleration is 26.8224 divided by the time in seconds. A car that reaches 60 mph in 6 seconds averages 4.47 m/s², or about 0.46 g.
What is a gal?
The gal (or galileo) is the CGS unit of acceleration, 1 cm/s², or 0.01 m/s². Geophysicists use it, usually as the milligal, to measure tiny differences in gravity when surveying for oil, minerals or underground cavities.