How this calculator works
Standard gravity provides a fixed acceleration scale: divide metres per second squared by 9.80665 to obtain a value in g units. Velocity mode calculates average acceleration along one signed axis; it cannot recover peak acceleration from endpoints alone. A negative value indicates direction, such as braking with forward velocity positive. Gravity mode instead estimates the field outside a spherical source. Neither scalar model predicts what an accelerometer or passenger feels. Proper acceleration depends on support forces: a freely falling accelerometer reads near zero while a supported stationary one near Earth reads about 1 g.
Formula
a_average = (v_final - v_initial)/t; g_units = a/9.80665; t = (v_final-v_initial)/(g_units x 9.80665). For a spherical gravitational source, a = GM/r².
Worked example
Speed increasing from 0 to 19.6133 m/s in 2 s gives average acceleration 9.80665 m/s² or 1 g. Braking from 19.6133 m/s to rest in 1 s gives -19.6133 m/s² or -2 g along the chosen forward axis.
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Frequently asked questions
Is a negative result a negative load on my body?
It specifies direction along the chosen axis. Felt load also depends on gravity, support direction and rotation, which this average-acceleration calculation does not combine.
Why does free fall feel weightless?
Gravity still changes velocity, but an unsupported accelerometer falls with its case and registers little proper acceleration.
Can I use average g to estimate an impact peak?
No. An impact pulse can have a much larger peak than the average over the entered interval. Time-resolved measurements are needed.