Question

what is the formula for opportunity cost

Answer 1

There is no universal formula. Generally, however, opportunity cost is merely the next best thing you could get if you spent your resources a different way. Say, in a world where there is a 5% interest rate on all money - the opportunity cost of a one-year investment is money invested*0.05 (the amount of money you could earn on the money if you chose to put it in a bank to reap interest, instead of investing it).