A ratio used to determine a stock's value while taking into account earnings growth. The calculation is as follows: Taobiz explains Price/Earnings To Growth - PEG Ratio PEG is a widely used indicator of a stock's potential value. It is favored by many over the price/earnings ratio because it also accounts for growth. Similar to the P/E ratio, a lower PEG means that the stock is more undervalued. Keep in mind that the numbers used are projected and, therefore, can be less accurate. Also, there are many variations using earnings from different time periods (i.e. one year vs five year). Be sure to know the exact definition your source is using.