There are a few ways to calculate a p-value in Excel. One way is to use the function T.DIST.2T(x,deg_freedom,tails). This function will calculate the p-value for a two-tailed test with the given degrees of freedom and tail value. Another way to calculate a p-value in Excel is to use the function T.INV.2T(p,deg_freedom,tails). This function will calculate the p-value for a two-tailed test with the given p-value and degrees of freedom.