How to use the acceleration converter
- Type the acceleration in Value.
- Choose the unit in From, for example standard gravity (g).
- Choose the unit you want in To, such as m/s² or ft/s².
- Read the answer and the table of all nine units. The swap button reverses the direction.
What it does and when to use it
Acceleration is how fast speed changes. Physics and engineering use m/s². American texts use ft/s². Pilots, ride designers and crash testers talk in g. Car magazines describe performance in km/h or mph gained per second. Geophysics uses Gal and milligal for tiny gravity differences. This tool converts between all of these with exact factors.
Typical jobs: turning an accelerometer reading in g into m/s² for a calculation, checking a physics answer given in ft/s², estimating the average g of a car’s acceleration from its 0–100 km/h time, or converting a gravity survey anomaly in mGal into SI. To change the speed units themselves, use the speed converter.
How it works
Every unit is stored in m/s². The result is value × from-factor ÷ to-factor.
| Unit | m/s² | Basis |
|---|---|---|
| standard gravity (g) | 9.80665 | 3rd CGPM, 1901 |
| ft/s² | 0.3048 | international foot |
| in/s² | 0.0254 | international inch |
| cm/s², Gal | 0.01 | CGS |
| milligal | 0.00001 | 1/1,000 Gal |
| km/h per second | 1 ÷ 3.6 ≈ 0.277778 | 1,000 m ÷ 3,600 s |
| mph per second | 0.44704 | 1,609.344 m ÷ 3,600 s |
Every factor is exact, so 1 g = 32.1740485564 ft/s² is a rounded display of an exact ratio (9.80665 ÷ 0.3048).
Worked examples
g to imperial. 1 g = 32.1740485564 ft/s², the “32.2 ft/s²” in American physics books.
Car acceleration. 0–100 km/h in 5 seconds is 20 km/h per second, which is 0.56650900721 standard gravity (g), or 5.55555555556 m/s². This is an average; the real push is stronger at first and weaker near the top.
Gravity surveys. 1 g = 980,665 milligal. A local anomaly of a few milligals is therefore a change of a few millionths of g.
Limits and tips
- Average versus peak. A single conversion cannot tell you peak g in a crash or on a ride; that needs a time-based measurement.
- Local gravity is not exactly g. The real value depends on where you are. Use the measured local value if your work needs it.
- For distance travelled from rest under constant acceleration, s = ½at², work in m/s² and seconds, then change the metres to feet or miles with the length converter.
Frequently asked questions
What is 1 g in m/s²?
How do I work out the g-force of a car's 0 to 100 km/h time?
What is a Gal?
Is g-force the same as weight?
Can I enter a negative acceleration?
Sources
- NIST Guide to the SI, Appendix B.8: Factors for units listed alphabetically — NIST, accessed 2026-10-08
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