Acceleration Converter – m/s², g-force and ft/s²

Acceleration units

Acceleration is the rate at which velocity changes. The SI unit is the metre per second squared (m/s²): an object accelerating at 1 m/s² gains 1 m/s of speed every second. The converter also supports:

• Standard gravity (g) = 9.80665 m/s², the conventional value of acceleration due to gravity at sea level
• Foot per second squared (ft/s²) = 0.3048 m/s²

One g is therefore about 32.174 ft/s².

What is g-force?

“g-force” expresses acceleration as a multiple of standard gravity. Standing still on Earth you experience 1 g. Some typical values:

• A passenger car braking hard: about 0.8–1 g
• A roller coaster: up to around 4–5 g for a moment
• A fighter pilot in a tight turn: up to about 9 g with a g-suit
• A Formula 1 car braking: around 5–6 g

Short peaks can be much higher than what people tolerate for several seconds, so g-force figures always depend on duration.

Acceleration of cars

Car performance is usually given as the time from 0 to 100 km/h or 0 to 60 mph. You can estimate the average acceleration: 100 km/h is 27.8 m/s, so reaching it in 8 seconds is an average of 3.5 m/s², or 0.35 g. A car that does 0–100 km/h in 2.8 seconds averages about 1 g – as fast as an object in free fall.

Gravity on other bodies

Gravity varies slightly on Earth – about 9.78 m/s² at the equator and 9.83 m/s² at the poles – which is why standard gravity is a fixed reference value. On the Moon, gravity is about 1.62 m/s² (0.17 g) and on Mars about 3.71 m/s² (0.38 g).

Sensors and accelerometers

Phones, fitness trackers and drones contain accelerometers that report values in m/s² or in g. A phone lying flat on a table shows about 9.81 m/s² on its vertical axis because it measures the support force against gravity.

Sources

Conversion factors follow the SI definitions in the BIPM SI Brochure and the exact factors for US customary and imperial units in NIST Special Publication 811.