The price to sales ratio can be calculated as:
Latest transacted price / Sales revenue per share
Comparing 2 companies with equal growth rates and financial strength, the one with a lower price to sales ratio may be more undervalued compared to the one with a higher price to sales ratio.
Looking at the price to sales ratio is not enough. One also has to look at other factors such as the price to earnings ratio, PEG ratio and more to determine if an underlying security will do well over the medium to long term.