Forward PS ratio is calculated as close price of the stock divided by estimated revenue per share of the company for the current financial year. If the current stock price is Rs.300 and estimated revenue per share of the company for the current financial year is Rs.80, then forward PS ratio is 300/80 = 3.75 .
Forward PS ratio can be used by comparing it with the current PS ratio of the company. Suppose current PS ratio of company A is 3x and the forward PS ratio is 1.8x, it indicates that the revenue of the company is expected to grow over the next year. The deeper the discount between current PS ratio and the forward PS ratio, the higher the potential for the stock price to increase.