Acceleration Converter
Convert acceleration between metres per second squared, feet per second squared, Gal (the geophysics unit of one centimetre per second squared) and g-force. The g-force unit is referenced to standard gravity, gₙ = 9.80665 m/s² — a defined constant adopted internationally, not a local measurement. Real gravity varies by about half a percent between the equator and the poles, but the standard value is what g-force, kilogram-force and “1 g” always mean.
How to use this tool
- Enter an acceleration value.
- Choose the unit you are converting from — including g-force for multiples of gravity.
- Choose the unit you want the answer in.
- Read the result, or switch on “show every equivalent unit” to see all four at once.
- Remember the g-force conversion uses standard gravity, not the gravity at your location.
The formula
Acceleration is the rate of change of velocity, with the SI base unit of metre per second squared. The g-force unit expresses it as a multiple of standard gravity, gₙ = 9.80665 m/s², a defined constant.
base_m/s² = value × (m/s² per unit)
result = base ÷ (m/s² per target)
1 g = 9.80665 m/s²- g
- Standard gravity, 9.80665 m/s² by definition
- Gal
- CGS unit, 1 cm/s² = 0.01 m/s²
Standard gravity is a fixed reference, not the local value: real gravity varies by about 0.5% between the equator and the poles.
Worked examples
Everyday gravity
- Given
- 1 g
- Result
- 9.80665 m/s²
One g is standard gravity exactly, the acceleration of a free-falling object at sea level.
A hard-braking car
- Given
- 1 g of braking
- Result
- ≈ 9.81 m/s²
A car braking at 1 g slows at about 9.81 m/s² — near the grip limit of ordinary tyres.
Seismic reading
- Given
- 50 Gal
- Result
- 0.5 m/s²
Ground acceleration in earthquakes is often quoted in Gal; 50 Gal is 0.5 m/s², about 0.05 g.
Frequently asked questions
It expresses acceleration as a multiple of standard gravity, 9.80665 m/s². At rest you feel 1 g; an acceleration of 2 g feels like twice your weight pressing on you. It is a ratio, so it has no units of its own beyond “g”.
The reference value is. Standard gravity is a fixed defined constant, so “1 g” always means 9.80665 m/s². Actual local gravity differs slightly with latitude and altitude, but g-force conversions use the standard value by convention.
The Gal, named after Galileo, is the CGS unit of acceleration: one centimetre per second squared, or 0.01 m/s². It is used in geophysics and gravimetry, where the milligal resolves tiny variations in the Earth’s gravity field.
Speed is how fast you are moving; acceleration is how quickly that speed is changing. A car at a steady 100 km/h has high speed but zero acceleration; one pulling away from a stop has rising speed and positive acceleration.
Engineering and physics work is usually in SI (m/s²), while some US sources and older texts use ft/s². Since a foot is exactly 0.3048 m, one ft/s² is exactly 0.3048 m/s², an exact conversion.