How is an award for pain and suffering calculated?

There is no hard-and-fast rule. Generally, pain-and-suffering awards are only appropriate when there has been permanent disability or disfigurement, or severe injury (serious fracture or worse) with at least temporary loss of some function. If an injury meets that benchmark, usually P&S awards are something like 1 - 3 times the medical costs, with greater periods of disability and/or residual loss of function leading to higher awards.