Free Fall Calculator
Fall time and impact speed, with or without air resistance.
About this tool
Enter the drop height and choose the gravity. Tick 'include air resistance' to add mass, drag coefficient, frontal area and air density, or pick a preset such as a skydiver, a ball or a raindrop.
Falling with and without air
In a vacuum, everything falls with the same acceleration g, 9.81 m/sยฒ on Earth. The fall time is t = โ(2h รท g) and the impact speed v = g ร t, so a 100 m drop takes 4.52 seconds and ends at 44.3 m/s (159 km/h). In air, drag rises with the square of speed until it equals the weight at the terminal velocity, v_t = โ(2mg รท (ฯ C_d A)). With air resistance on, the tool uses the exact solution for quadratic drag, h = (v_tยฒ รท g) ln cosh(g t รท v_t). A belly-down skydiver reaches about 50 m/s (180 km/h); head-down it's well over 100 m/s; a 2 mm raindrop tops out at about 6.5 m/s. The same 100 m drop for the skydiver takes 4.8 s and ends at 37 m/s. Honest limits: drag coefficients and areas are approximate and change as objects tumble or spread out, and air thins with altitude, so very high falls reach higher speeds than shown. The SUVAT calculator and the projectile motion calculator are related.
Frequently asked questions
How long does it take to fall 100 m?
About 4.5 seconds without air resistance, reaching 44 m/s. With air resistance it takes a little longer.
What is the free fall formula?
Time t = โ(2h รท g) and impact speed v = g ร t = โ(2gh), ignoring air resistance.
What is a skydiver's terminal velocity?
About 50 to 55 m/s (180 to 200 km/h) belly-down, and much faster head-down.
Do heavier objects fall faster?
Not in a vacuum. In air, heavier objects of the same shape have a higher terminal velocity, so they fall faster.
Is my data sent anywhere?
No. Everything is calculated in your browser, and nothing is stored or sent.