G-Force Calculator

A g is a unit of acceleration equal to the pull of gravity at the Earth’s surface, about 9.81 meters per second squared. Saying something pulls 2 g just means it is accelerating twice as hard as a dropped object speeds up. It is a handy unit because it maps onto a feeling everyone knows: 1 g is your normal weight, and higher g-force is that pressed-into-the-seat sensation.

The math is simple. Acceleration is the change in speed divided by the time it takes, and g-force is that acceleration divided by 9.81. So a car going from 0 to 60 miles per hour in 3 seconds is changing speed by about 26.8 meters per second over 3 seconds, which is roughly 8.9 meters per second squared, or just under 1 g. This calculator takes your speed change and time, handles the unit conversion, and gives you both the acceleration and the g-force.

For a sense of scale: a brisk elevator is around 0.2 g, a hard-braking car can hit 1 g, a sharp roller-coaster pulls 4 to 5 g, and aerobatic pilots and fighter jets briefly see 9 g or more. What your body can take depends heavily on how long it lasts and which direction it points. A brief spike in a car crash can reach dozens of g and be survivable, while a sustained few g pushing blood away from the brain will make a pilot grey out in seconds. This figure assumes a steady acceleration over the time you enter, so it gives the average rather than a peak.