Price to earnings ratio: A comprehensive guide

price earning ratio comprehensive guide

What is the price-to-earnings (P/E) ratio?

The price-to-earnings (P/E) ratio is a valuation metric for a company’s stock that compares the current share price to its per-share earnings. It’s used to evaluate whether a stock is fairly valued, overvalued, or undervalued by the market. The P/E ratio shows how much investors are willing to pay for a dollar of the company’s earnings, providing insight into market expectations of a company’s growth and profitability.


Price earnings ratio formula

To determine the P/E ratio, one simply divides the price per share of the stock by the company’s earnings per share (EPS). Here is the basic equation:

P/E Ratio = Market Value per Share / Earnings per Share

Price to Earnings Ratio formula


  • Share Market Value is the present trading price of the company’s stock.
  • Earnings per Share (EPS) represents the segment of a company’s profit attributed to each share in circulation, as detailed in the company’s financial earnings statement.

The earnings used in this formula can either be from the last four quarters (trailing P/E) or forecasted for the next four quarters (forward P/E). The choice between trailing or forward EPS changes the perspective from a historical to a predictive measure, and it can significantly affect the resulting P/E ratio.

Why use the price earnings ratio?

The Price Earnings Ratio (P/E Ratio) is used for several reasons in financial planning and analysis. Its primary function is to assist investors in gauging the stock’s market value in relation to the company’s earnings, thereby assessing the amount investors are prepared to spend for each dollar of earnings. A higher P/E ratio might indicate that a stock is expensive relative to earnings, while a lower P/E suggests it may be undervalued. The P/E ratio is instrumental in assessing whether a company’s stock price is aligned with its earnings performance, making it a fundamental tool for comparing the financial health and growth potential of similar companies within the same industry or sector.

When to review the P/E ratio

The P/E ratio should be reviewed whenever an investor is considering buying or selling a stock, especially when analyzing a company’s financial stability and growth prospects. It is also crucial to review the P/E ratio during earnings announcements, as changes in earnings can significantly affect the company’s valuation. Additionally, the P/E ratio can be a valuable metric to monitor during market fluctuations, as it may highlight opportunities where the market has mispriced stocks relative to their earnings. Investors may also review the P/E ratios as part of a broader investment strategy review, whether quarterly, annually, or at other regular intervals.

Price earning ratio example

Example of the P/E ratio

For example, take a company whose stock is presently priced at $100 and it has an earnings per share (EPS) of $5. The calculation of the P/E ratio would proceed as below:

P/E Ratio = Share Market Value / EPS

P/E Ratio = $100 (Share Market Value) / $5 (EPS) = 20

This suggests investors are prepared to spend $20 for every dollar of the company’s earnings. When evaluated against the average industry ratios and the company’s historical earnings data, this ratio may indicate if the stock is priced below or above its intrinsic value.

Limitations of price earnings ratio

Limitations of price earnings ratio

While the P/E ratio is a valuable indicator of stock valuation, it has limitations. It doesn’t account for company debt, doesn’t distinguish between capital-intensive and light-asset businesses, and is less relevant for companies with negative earnings.

Additionally, the P/E ratio may be influenced by external elements like tax regulations and accounting methods that could skew the earnings figure. Hence, it should be used in conjunction with other FP&A tools.

Other P/E considerations

In addition to the standard P/E ratio analysis, investors should consider variants such as the cyclically adjusted price-to-earnings (CAPE) ratio, which smooths out earnings over a longer period to account for economic cycles. Sector-specific P/E benchmarks are also important, as they provide a more relevant comparison between similar companies, acknowledging that different industries have different average P/Es.

What is a good price-to-earnings ratio?

What constitutes an advantageous P/E ratio is relative, hinging on the specific sector, prevailing market climates, and the particular growth expectations for the company. A P/E lower than the industry average might indicate an undervalued stock, while a higher P/E may suggest overvaluation or expectations of strong growth. It’s important to compare the P/E ratio with historical company averages and industry standards to make a more informed judgment.

Price earning ratio explained

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