How do you calculate force needed to pull apart an object?

[Bubba]

I am trying to figure out how to calculate the force it takes to pull a chin strap from a helmet. Is there a special scale that you can use? I am not in school anymore and it has been years since I have done any math or science, so small words are greatly appreciated.

 

[Pierce610]

According the international standard the force to pull the chin strap of an industry helmet is 25 Newton.
Newton is the unit for the force in the International System of measure.