How to calculate the price-to-earnings (P/E) ratio

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Understanding the value of a stock is crucial before making an investment decision. One key metric that offers insights into the value of a stock is the price-to-earnings (P/E) ratio. Let’s take a closer look at the P/E ratio metric to understand what it is, how it is calculated, and what it can tell us.

  • Table of contents
  1. Understanding P/E ratio
  2. How to calculate P/E ratio
  3. Factors influencing the P/E ratio
  4. What does the P/E ratio tell us about a stock
  5. Factors to keep in mind about P/E ratio
  6. FAQ

Understanding P/E ratio

The P/E ratio is a metric that allows investors to compare the market value of a stock to the company’s earnings. It essentially tells us about the price an investor is willing to pay for a stock relative to the company's past or projected earnings.

High P/E ratio: For example, if a stock has a high P/E ratio, it might indicate that its price is high in relation to its earnings, suggesting that it is possibly overvalued.

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Low P/E ratio: On the other hand, a low P/E may show that the stock price is low compared to its earnings, suggesting that it might be undervalued. However, it is essential to ascertain if this low valuation is due to consistent underperformance.

This ratio can give investors a clear picture of a company's value and help them to determine the worth of the stock based on its earnings.

How to calculate P/E ratio

The P/E ratio offers a simple way to assess the market's valuation of a company in relation to its earnings. To calculate the P/E ratio, you need two pieces of information: the market price of a share and its earnings per share (EPS).

The PE ratio formula is as following:

P/E Ratio = Market Price Per Share/ Earnings Per Share (EPS)

As an example, consider company XYZ. Suppose the current market price of its share is Rs. 100. Over the last financial year, company XYZ reported earnings per share (EPS) of Rs. 10. When we add these values into the formula, this is what we get:

P/E ratio = 100/10 = 10

This means that for every rupee of earnings the company XYZ generates, investors are willing to pay Rs. 10. In essence, it provides a valuation multiple.

Additionally, EPS is a significant component of the P/E ratio. It is calculated as:

EPS = Net Earnings / Number of Outstanding Shares

‘Net Earnings’ refers to the total profit of the company after deducting all expenses, including taxes. ‘Number of outstanding shares’ represents the total number of shares that are currently held by all shareholders.

Factors influencing the P/E ratio

While the calculation is straightforward, it is essential to note that several factors can influence a company's P/E ratio:

Growth prospects: Companies expected to grow and expand rapidly often have relatively higher P/E ratios. The market anticipates these companies will have higher earnings in the future, justifying a higher valuation today.

Risk profile: Companies in volatile markets or with unstable earnings may have lower P/E ratios. Investors might not be willing to pay as much for returns that aren't consistent.

Industry norms: Every industry has a different average P/E ratio. For instance, technology companies might traditionally have higher P/E ratios than manufacturing firms.

Economic environment: During economic booms, optimism may drive higher P/E ratios. During downturns, P/E ratios might contract.

What does the P/E ratio tell us about a stock?

High P/E: Stocks with a high P/E indicate investors' expectations of significant future earnings growth. While this suggests positive future performance, these stocks can be unpredictable, potentially making them riskier investments.

Low P/E: Companies with a low P/E often seem undervalued, possibly indicating weak current or future performance. However, if the company has robust fundamentals, it might be a good investment.

Justified P/E: The justified P/E is calculated differently from the standard P/E. If a company's P/E is lower than its justified P/E, it might be undervalued, making it a potential profit-generating investment.

Negative P/E: Companies with negative earnings will have a negative P/E. It's crucial to be wary of investing in businesses with consistently negative P/E ratios, as they might be on the brink of bankruptcy.

Factors to keep in mind about P/E ratio

While the P/E ratio is a valuable tool, relying only on this single metric could be misleading. Here are some other factors to consider:

Exclusion of debt:The P/E ratio doesn't consider a company's debt, potentially overlooking highly leveraged (and possibly riskier) firms.

Earnings volatility: The metric assumes stable future earnings. However, earnings can be volatile, influenced by various factors.

Unclear growth direction: The P/E ratio doesn’t indicate the growth direction of a company’s cash flow, leading to potential misconceptions.

Earnings quality: A lower P/E ratio doesn't necessarily indicate a better investment. The quality of earnings also matters.


The P/E ratio is certainly an important tool for investors, offering insights into a stock's value compared to its earnings. However, when considering an investment, it is crucial to combine P/E ratio with other metrics and thorough research for a holistic view of the stock's potential. Always remember, when in doubt, it is prudent to consult a financial advisor before making any investment decisions.


What is the significance of the P/E ratio in stock analysis?
The P/E ratio is a crucial valuation metric that indicates how much investors are willing to pay for each rupee of a company's earnings. A higher P/E ratio typically suggests that investors have higher expectations for future earnings growth.

How do you calculate the P/E ratio?
To calculate the P/E ratio, divide the current market price of a stock by its earnings per share (EPS) for a specific period, usually the past 12 months. It's a simple formula: P/E Ratio = Market Price per Share / Earnings per Share.

What does a high or low P/E ratio imply?
A high P/E ratio can suggest that a stock may be overvalued, while a low P/E ratio may indicate undervaluation. However, it's essential to consider industry norms and the company's growth prospects for a more accurate assessment.

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This document should not be treated as endorsement of the views/opinions or as investment advice. This document should not be construed as a research report or a recommendation to buy or sell any security. This document is for information purpose only and should not be construed as a promise on minimum returns or safeguard of capital. This document alone is not sufficient and should not be used for the development or implementation of an investment strategy. The recipient should note and understand that the information provided above may not contain all the material aspects relevant for making an investment decision. Investors are advised to consult their own investment advisor before making any investment decision in light of their risk appetite, investment goals and horizon. This information is subject to change without any prior notice.