Payback is the amount of time needed for an investment to earn its cost, undiscounted. Years ago as a young analyst, I was assigned the project of streamlining my employers’ acquisition model. As part of this project, I removed the payback calculation. The company’s focus was on discounted cash flow and internal rate of return, so I didn’t see the need for a payback metric. No one noticed the missing payback calculation, that is, no one except the CEO.