PEG Ratio Calculator
Evaluate stock valuation by comparing PE ratio to earnings growth rate.
For educational purposes only. This calculator does not provide investment advice.
📊 Visual Analysis
What This Calculator Does
The PEG Ratio Calculator divides the Price-to-Earnings (P/E) ratio by the assumed earnings growth rate to produce the PEG ratio. This metric helps contextualize a company's valuation by factoring in how quickly its earnings are growing. Enter the P/E ratio and the assumed annual earnings growth rate to see the PEG value and an interpretation of what it means.
Formula
Where:
- PEG = Price/Earnings-to-Growth ratio
- P/E Ratio = Current share price divided by earnings per share (trailing or forward)
- Earnings Growth Rate = The assumed annual percentage growth in earnings per share
The PEG ratio normalizes the P/E by growth, allowing investors to compare valuations across companies with different growth rates. A PEG of 1.0 means the P/E ratio equals the growth rate, but this is not a universal rule for fair value.
Input Fields Explained
PE Ratio
The company's price-to-earnings ratio. This can be a trailing P/E (based on past 12 months of earnings) or a forward P/E (based on projected earnings). Make sure you know which one you are using, as they can differ significantly. Forward P/E with forward growth assumptions is a common pairing.
Assumed Earnings Growth Rate (%)
The annual percentage rate at which you assume earnings per share will grow. This is a modeling input, not a forecast or guarantee. Growth estimates often come from analyst consensus, historical trends, or your own analysis. The PEG ratio is only as reliable as the growth assumption behind it.
Example Calculation
A stock has a P/E ratio of 25 and an assumed earnings growth rate of 20% per year.
PEG = 25 ÷ 20 = 1.25
Interpretation: The PEG of 1.25 means the P/E ratio is 1.25 times the growth rate. Whether this represents reasonable value depends on industry norms, growth sustainability, and broader market conditions. A PEG above 1.0 does not automatically mean overvalued, just as a PEG below 1.0 does not guarantee undervaluation.
How to Read the Result
The PEG ratio result. A lower PEG suggests the stock may be more attractively valued relative to its growth rate, while a higher PEG suggests the market is pricing in significant growth expectations. No single PEG value is universally good or bad — context matters.
Common Mistakes
- Using historical growth to predict the future. Past earnings growth does not guarantee future growth. Using a trailing growth rate with a forward P/E creates a mismatch. Align the time horizon of both inputs for a consistent calculation.
- Treating PEG < 1 as a buy signal. A PEG below 1.0 is sometimes cited as attractive, but this is a rule of thumb, not a principle. A low PEG can result from a depressed stock price due to fundamental problems, not undervaluation. Always investigate why the PEG is low.
- Ignoring growth quality. Not all growth is equal. Organic revenue-driven growth is generally more sustainable than growth from acquisitions or one-time events. The PEG ratio treats all percentage growth the same, regardless of source.
- Applying PEG to negative-growth stocks. When earnings are declining, the PEG ratio becomes negative and loses meaning. PEG is designed for companies with positive, ideally stable, earnings growth.
- Relying on a single metric. PEG is one data point among many. It does not account for debt levels, cash flow, dividend policy, competitive dynamics, or management quality. Use it alongside other valuation tools.
When This Calculator Is Useful
- Comparing valuations of growth stocks with different P/E ratios and growth rates
- Assessing whether a high P/E might be justified by high earnings growth
- Screening for stocks that may be reasonably valued relative to their growth trajectory
- Contextualizing P/E ratios within a growth framework
Limitations
- Depends entirely on the accuracy of the assumed growth rate, which is uncertain
- Not applicable to companies with negative or highly variable earnings growth
- Ignores dividends, debt levels, cash flow, and capital structure
- Treats all growth as equal regardless of source or sustainability
- Less useful for value stocks, financial companies, and cyclical businesses
- This calculator is for educational purposes only and does not constitute investment advice
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Frequently Asked Questions
What is the PEG ratio?
The PEG ratio (Price/Earnings-to-Growth) divides a stock's P/E ratio by its earnings growth rate. It provides a way to compare valuations across companies with different growth profiles by accounting for how fast earnings are expanding. A lower PEG may suggest a stock is more reasonably valued relative to its growth, while a higher PEG may suggest the opposite — though no single threshold applies universally.
How does PEG differ from P/E ratio?
The P/E ratio measures how much investors pay per dollar of current earnings, without considering growth. Two companies with the same P/E can have very different growth trajectories. The PEG ratio adjusts the P/E by dividing it by the growth rate, allowing comparison between high-growth and slower-growth companies. This makes PEG more useful when evaluating growth stocks, but less meaningful for companies with low or negative growth.
What is a good PEG ratio?
There is no universally good PEG ratio. A common reference point is that a PEG of 1.0 means the P/E equals the growth rate, but this is not a rule or a guarantee of fair value. Whether a PEG is attractive depends on the industry, the quality and sustainability of the growth rate, interest rate conditions, and the broader market environment. A PEG below 1 does not automatically mean a stock is undervalued.
Why does growth rate matter?
The growth rate used in the PEG ratio contextualizes the P/E multiple. A company with a P/E of 30 growing earnings at 30% per year has a PEG of 1.0, while the same P/E with 10% growth produces a PEG of 3.0. Without the growth rate, the P/E alone cannot distinguish between a company growing rapidly (which may justify a higher multiple) and one growing slowly (which may not). The growth rate is always an assumption or estimate, not a certainty.
What are the limitations of the PEG ratio?
The PEG ratio relies on an assumed growth rate, which is inherently uncertain. Analysts often disagree on growth projections, and actual results frequently differ from estimates. PEG also ignores dividends, debt levels, and cash flow. It treats all growth as equal regardless of quality (organic vs. acquisition-driven), and it is not meaningful for companies with negative or highly cyclical earnings growth.
Does PEG work for all stocks?
No. The PEG ratio is most relevant for companies with stable, positive earnings growth. It is not useful for companies with negative earnings, declining growth, or highly cyclical businesses where growth rates swing dramatically. Value stocks, turnaround situations, and financial-sector companies are generally poor candidates for PEG analysis. For these, metrics like P/B, EV/EBITDA, or dividend yield may be more appropriate.
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Educational Disclaimer
This calculator is for educational and informational purposes only. It does not provide investment, financial, tax, or legal advice. The results are based on the inputs and assumptions you provide and may not reflect real market conditions, fees, taxes, or risks. Always do your own research or consult a qualified professional before making financial decisions.