What Is P/E Ratio? What Does It Mean? How Do You Use It?

The P/E Ratio is one of the most fundamental metrics any investor should check when researching a company — yet it’s also one of the most commonly misunderstood.

Here’s what we’ll cover:

1. What does P/E Ratio mean?
2. How is it calculated?
3. When should you invest based on it?
4. Is a higher or lower P/E better?

What Is P/E Ratio?

P/E Ratio stands for Price-to-Earnings Ratio. In simple terms, it tells you how much investors are collectively willing to pay for ₹1 (or $1) of a company’s profit.

Put differently: it’s a measure of how many times a company’s earnings investors are willing to pay to own a share of it.

How Is P/E Ratio Calculated?

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

To get there, you first need EPS:

EPS = PAT (Profit After Tax) ÷ Total Number of Outstanding Shares

A Worked Example

Say a company has:

• Current Share Price = ₹20
• PAT = ₹5,000
• Outstanding Shares = 10,000

(A simplified, illustrative example — real company data can be found on most stock screeners or financial data sites.)

Step 1 — Calculate EPS:

EPS = PAT ÷ Outstanding Shares = 5,000 ÷ 10,000 = ₹0.5

Step 2 — Calculate P/E Ratio:

P/E Ratio = Share Price ÷ EPS = 20 ÷ 0.5 = 40

So in this example, investors are willing to pay ₹40 for every ₹1 of this company’s profit. In practice, you’ll rarely need to calculate this yourself — P/E ratios are readily available on virtually any stock screener or financial site.

When Should You Invest Based on P/E Ratio?

There are two common ways to use P/E as a comparison tool:

1. Compare it to the industry average. A sector’s average P/E is essentially the average of every company’s P/E within that industry. For example, the IT sector’s average P/E reflects the typical valuation across IT companies broadly. Comparing an individual company’s P/E to this average gives you a sense of whether it’s overvalued or undervalued relative to its peers.

2. Compare it to a similar company. If you’re deciding between two comparable companies, comparing their P/E ratios can be one useful data point — though it shouldn’t be the only one.

Important caveat: a lower P/E isn’t automatically the better choice.

Is a Higher or Lower P/E Better?

A common misconception is that a low P/E ratio automatically signals a good value-investing opportunity. That’s not quite right — P/E is one input into value investing, not a standalone decision-making tool.

→ Related: What Is Value Investing?(#13)

A low P/E can genuinely reflect an undervalued company — or it can reflect a company that’s underperforming and priced accordingly. A high P/E can reflect an overvalued company — or a genuinely strong, high-growth business that the market is willing to pay a premium for.

The key is understanding why a company’s P/E is where it is. Is a high P/E backed by strong, sustained performance, or is the stock just overhyped? Is a low P/E a genuine bargain, or a red flag about the underlying business? Answering that question is what actually determines whether the P/E ratio is telling you something useful.

→ Related: How to Find the Intrinsic Value of a Share/Stock(#14)

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P/E Ratio is a genuinely useful tool — just not a standalone one. Use it alongside other research, not as the sole basis for any investment decision. Thanks for reading.