Acceleration

Acceleration measures how quickly velocity changes over time. The SI unit is metres per second squared (m/s²). A dropped object in Earth's atmosphere accelerates at roughly 9.8 m/s², the value codified as standard gravity g₀ = 9.80665 m/s² by the CGPM in 1901 and used today in the definitions of the pound-force and the kilogram-force. Because this constant shows up in three different unit systems, any mistake in its value propagates into every force and pressure calculation that follows.

The foot per second squared (ft/s²) is the US-customary counterpart, with 1 ft/s² equal to exactly 0.3048 m/s². Engineering texts in feet-pound-second units typically use ft/s², while physics and scientific work use m/s². The centimetre per second squared (cm/s²), also called the gal or galileo after its namesake, is the workhorse of geophysics and gravimetry because natural gravitational anomalies are too small to show up at m/s² resolution.

Car spec sheets rarely list acceleration directly but imply it: a 0–60 mph run in 3.0 seconds averages about 8.94 m/s², or 0.91 g. Electric hypercars like the Rimac Nevera post sub-2-second runs, which averages above 1.5 g — a value that pushes hard against what tires can transmit on dry pavement. Aerospace engineers state sustained g-loads in multiples of g₀: a modern fighter endures 9 g in hard turns, the Space Shuttle peaked near 3 g on launch, and an F-16 ejection seat imposes 14 g on the pilot for a fraction of a second.

Geophysicists use milligals (10⁻³ cm/s²) and microgals to detect underground density variations caused by oil reservoirs, salt domes, and buried structures. A granite outcrop produces a measurable positive anomaly at the micrometer-per-second-squared scale. That same extreme sensitivity means acceleration conversion must stay exact through many orders of magnitude.

Our converter supports seven acceleration units — m/s², cm/s², ft/s², in/s², km/h/s, mph/s, and standard gravity g — with the exact CGPM value of g₀ and exact imperial conversion factors (1 ft = 0.3048 m, 1 mile = 1609.344 m). Engineering, automotive, seismology, and physics calculations stay coherent across all these units.