Acceleration converter

Exactly 9.80665 m/s², the standard acceleration of gravity adopted by the 3rd General Conference on Weights and Measures in 1901. It equals 32.174 ft/s². Local gravity differs slightly; 9.80665 is the convention used for g-force and for units such as the kilogram-force.

Divide the speed gained by the time, then divide by 9.80665. 0–60 mph (26.8224 m/s) in 3 s averages 8.94 m/s², or 0.91 g; 0–100 km/h (27.78 m/s) in 3 s averages 9.26 m/s², or 0.94 g. The peak acceleration during the run is higher than this average.

One centimetre per second squared, 0.01 m/s², named after Galileo. Earth's surface gravity is about 980 Gal, so gravity surveys work in milligals, where 1 mGal is about one millionth of g. The symbol is Gal, and the unit has nothing to do with the gallon.

Multiply by 0.3048, the exact number of metres in a foot. 32.174 ft/s² is 9.80665 m/s² (1 g), and 10 ft/s² is 3.048 m/s². To go from m/s² to ft/s², divide by 0.3048, which is the same as multiplying by 3.28084.

No. Free-fall acceleration is about 9.780 m/s² at the equator and 9.832 m/s² at the poles, because the Earth spins and bulges at the equator, and it falls slightly with altitude. 9.81 is 9.80665 rounded, the conventional value between those extremes that g-force is measured against.

Accuracy depends on your inputs and the method's assumptions. Decimal arithmetic uses 50 significant digits, but estimates, numerical methods and source data can be less precise; the displayed rounding does not remove those limits. It is checked against 4 worked examples whose answers come from independent sources; for example, “1 g in m/s²” is checked against Standard gravity g₀ = 9.80665 m/s² exactly (CGPM 1901).

NIST SP 811 (2008), Guide for the Use of the SI, Appendix B — conversion factors; NIST Handbook 44, Appendix C — General tables of units of measurement.