这个跟到期日有关系的，一般交易所会公布系数，不用自己算

自己只需要挑选自己最核算的债券拿去交割就可以了。这与卖方有关。买方没得选

Conversion factors apply to quoted futures prices and convert it into cash price in T-bond futures calculation.

Hull introdued this in his book, which you may refer to.