Check this out.

So, the guy jumps from 150 feet into some cardboard boxes. Why are the boxes important? You want something that can stop you in the largest distance to make your acceleration the smallest. Here is my Dangerous Jumping Calculator. Basically, you put in how high you will jump from and how much distance you will take to land and it tells you your acceleration.

You will probably need this G-force tolerance info from wikipedia.

One problem – this calculator doesn’t really work for this case. It doesn’t take into account air resistance. Does air resistance even matter in this case? How about a plot of a person falling from 150 feet with and without air resistance? (I just used my code from the Red Bull Stratos Jump calculation)

This is a difference in speed of just about 3 m/s (or almost 7 mph). I guess every little bit helps.