Payback Time is the estimated time it will take for the stock to double. This is calculated based on the growth rate of the stock price. This number should not be taken literally. Payback Time should be used as a comparing tool against other stocks. For example a stock with a Payback Time of 3 years will most likely double faster than a stock with a Payback Time of 7 years. Important Note: If the Payback Time is 0 or a negative number, that means the stock is under performing.