Acceleration Converter
Convert between m/s², standard gravity (g), ft/s², and km/h per second.
How acceleration conversion works
Acceleration measures how quickly speed changes over time, so its units combine a distance unit with time squared. 'g' (standard gravity) is a convenient reference point — Earth's surface gravity — commonly used to describe forces felt in vehicles, roller coasters, and spacecraft.
Reference points
- 1 g ≈ 9.807 m/s² — the acceleration of a freely falling object near Earth's surface
- A car braking hard might reach 0.8–1 g; a fighter jet pilot might briefly experience 5–9 g in a turn
- 1 km/h per second ≈ 0.278 m/s² — a common way to express a car's 0-to-100-km/h acceleration rate
Units and factors
Meters per second squared is the base. One g is 9.80665 m/s², one ft/s² is 0.3048 m/s², and one km/h per second is 1000 ÷ 3600, about 0.277778 m/s². Output shows up to six decimals, updates as you type and uses your browser's digit grouping. The default converts 1 g to m/s².
Worked examples
- 1 g = 9.80665 m/s², and 9 g = 88.25985 m/s².
- 32.174 ft/s² = 0.999998 g, close to but not exactly 1 g.
- 10 km/h per second = 2.777778 m/s².
- 3.5 m/s² = 0.356901 g.
- 1 m/s² = 3.28084 ft/s².
A car acceleration figure
A car that reaches 100 km/h from rest in 8 seconds is gaining on average 100 ÷ 8 = 12.5 km/h each second. Enter 12.5 with km/h per second as the source: that is 3.472222 m/s², or 0.354068 g. The tool only converts; it does not divide speed by time for you, and it cannot tell you whether the acceleration was steady. Negative values (deceleration) are converted as typed.
Checking a result
One standard gravity is 32.174049 ft/s², and a vehicle gaining 60 km/h every second is accelerating at 16.666667 m/s², which is about 1.7 g. Negative values are accepted and keep their sign, which is handy for braking: -5 g is -49.03325 m/s². Standard gravity is taken as exactly 9.80665 m/s², so converting 9.80665 m/s² to g returns exactly 1.
Results are rounded to six decimal places, so a tiny value such as 0.000000001 g displays as 0 m/s². A very large entry such as 1e30 is printed out in full digits rather than in scientific notation.
Frequently asked questions
Why is 'g' used instead of m/s² for things like roller coasters?
Because it's a relatable reference: 1 g is what you feel constantly from Earth's gravity, so describing a ride as '3 g' immediately conveys that it feels three times as strong as normal gravity, which is more intuitive than a raw m/s² number.
Is 'g' the same as 'g' for grams?
No — this is a common point of confusion. Lowercase 'g' for standard gravity (an acceleration) and 'g' for grams (a mass) are unrelated units that happen to share the same letter.
How do I convert 0-to-100 km/h time into m/s²?
Divide 100 by the time in seconds to get km/h per second, enter that number with km/h per second selected, and convert to m/s². An 8-second time gives 12.5, which is 3.472222 m/s².
Why does 32.174 ft/s² not give exactly 1 g?
The tool uses 9.80665 m/s² for g and 0.3048 m per foot. 32.174 ft/s² therefore comes to 0.999998 g, and the 32.174 you typed is itself a rounded figure.
Can I enter a negative acceleration?
Yes. Negative numbers are converted with the same factors and keep their sign.