Acceleration Converter
Same value in every unit
| Unit | Value |
|---|
Acceleration is a change in speed, not a speed
A speed says how fast something is going. An acceleration says how quickly that speed is changing — metres per second, per second. A car at a steady 100 km/h has zero acceleration however fast it feels; the same car braking hard has a large one.
What the numbers feel like
- 0.3 g — comfortable braking
- 0.8 g — hard braking on dry road, near the limit of ordinary tyres
- 1 g — the pull you feel standing still
- 3–4 g — a rollercoaster loop
- 9 g — a fighter aircraft turn, at the edge of what a trained pilot can stay conscious through
Why 9.80665 exactly
Standard gravity is a defined constant, agreed so that measurements are comparable, not a measurement of any particular place. Real local gravity ranges from about 9.78 m/s² at the equator to 9.83 at the poles, because the Earth is not a sphere and it spins. Geophysicists care about differences far smaller than that, which is why they work in milligals.
Converting a 0-to-60 figure
Take the change in speed and divide by the time. 0 to 100 km/h in 5 seconds is 20 km/h per second — pick that unit above and read off 5.56 m/s², or 0.57 g.
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Frequently Asked Questions
Standard gravity, defined as exactly 9.80665 m/s². It is a defined constant rather than a measurement, which is why the factor here is exact. Actual gravity varies slightly with latitude and altitude — a little under 9.78 at the equator and a little over 9.83 at the poles.
It is acceleration expressed as multiples of gravity. A brisk car braking is around 0.8 g, a fairground ride 3 to 4 g, and a fighter pilot in a hard turn may see 9 g. At 1 g you feel your own weight again in the direction of the acceleration.
It is the unit of geophysics and gravimetry, where the interesting variations in Earth's gravity are tiny. One gal is a hundredth of a metre per second squared, and surveys are usually quoted in milligals.
100 km/h in 5 seconds is 20 km/h per second, which is 5.56 m/s² or about 0.57 g. Converting it makes it comparable with everything else on the list.
No, it is worked out in your browser.