How To Calculate A Price To Earnings Ratio

The price to earnings ratio is the share price divided by earnings per share. A share trading at eighty with earnings of five has a ratio of sixteen, which is read as the market paying sixteen units for each unit of annual profit.

It is a valuation multiple rather than a verdict. A high ratio means the market expects profit to grow, or that the shares are expensive, or both. The ratio alone cannot tell you which, and treating it as a simple cheap or expensive signal is the most common misuse.

The denominator matters enormously. Trailing earnings use the last twelve reported months and are known facts. Forward earnings use analyst forecasts and are estimates. The two can differ substantially, and a ratio quoted without saying which is nearly meaningless.

Earnings per share itself is net income divided by the number of shares outstanding. Companies that issue new shares dilute it, and companies that buy back shares increase it without any change in total profit, which changes the ratio mechanically.

The inverse of the ratio is the earnings yield, which expresses profit as a percentage of the price. A ratio of sixteen corresponds to an earnings yield of 6.25 percent, which is directly comparable with bond yields and savings rates.

That comparison is the most useful thing about the ratio. If a share offers a 6.25 percent earnings yield while a risk-free government bond pays 4.5 percent, the equity is being priced for a fairly modest risk premium. It is not a recommendation, but it is a starting point.

The ratio breaks down when earnings are negative or near zero. A loss-making company has no meaningful P/E, and one with tiny earnings produces an enormous multiple that says nothing except that the denominator is small.

Earnings can also be flattered by one-off items. A company that sells a building shows a large profit that will not repeat, which depresses the ratio artificially and makes the shares look cheaper than they are. Adjusted earnings exist precisely to handle this.

Cyclical businesses invert the usual logic. At the top of a cycle their earnings are high and their ratio looks low, which is often a warning rather than a bargain. At the bottom the ratio looks terrible and may be the better moment.

Comparisons are only meaningful within an industry. Software companies and utilities trade on structurally different multiples because their growth rates and capital needs differ. A ratio of fifteen means something different in each.

Finally, the ratio says nothing about debt. Two companies with identical earnings and prices can have very different balance sheets, and the one carrying more debt is riskier for the same multiple. Enterprise value multiples exist to correct for exactly that.