As it is today you have normally no access to information on the different packaging materials capability of absorbing vibration. In principle you can use a combination of the E-modular from the ECT-test and Mc Kee’s formula to calculate the spring constant. Another way to have the spring constant is a compression test on the final box. Another way of finding the spring constant is a compression test of the final parcel.
The problem using formulas is that the real world is far more complex than our model. I.e. the staking pattern changes the forces and as described in F3: Test compression just a little displacement change all.