Freefall Calculator
How long do you have between exit and pull? Pick your body position, plug in altitudes, and we'll work out time on the dive, average speed, and speed at pull.
How it works: terminal velocity ramps from 0 to vt following a tanh curve; distance is the log-cosh of that ramp. You hit ~99% of terminal about 14.3 s into the skydive at the belly / rw / fs position — so most of freefall is at-speed.
Numbers are a physics approximation using constant drag — they'll be in the ballpark of what stopwatches and audibles actually read, but a quick hop & pop, strong body-position change mid-skydive, or wingsuit flare can skew them by a few seconds.
The math
Constant-drag vertical model with terminal velocity vt: velocity follows v(t) = vt · tanh(g·t / vt) and distance y(t) = (vt²/g) · ln(cosh(g·t / vt)). We invert y(t) to get t for your exit−pull. Terminal speeds come from typical freefly rigs (belly ~53 m/s, head-down ~80 m/s, wingsuit ~25 m/s); adjust with the custom option.
Concept reference: skydiverpal.com/tools/fftime