PEG Ratio Calculator

Calculate the price/earnings to growth (PEG) ratio to help assess whether a stock may be fairly valued based on earnings growth.

Enter P/E and growth rate to calculate PEG ratio

What Is the PEG Ratio?

The price/earnings to growth (PEG) ratio refines the standard P/E ratio by incorporating expected earnings growth. While the P/E ratio shows how much investors pay for each dollar of current earnings, the PEG ratio adjusts that figure to account for future earnings growth. A lower PEG ratio may suggest a stock is undervalued relative to its growth prospects, while a higher ratio could indicate overvaluation.

How the PEG Ratio Is Calculated

The PEG ratio is calculated by dividing the P/E ratio by the expected earnings growth rate.

PEG Ratio = P/E Ratio ÷ Earnings Growth Rate

For example, if a stock has a P/E ratio of 20 and an expected annual earnings growth rate of 15%, the PEG ratio is 1.33 (20 ÷ 15).

The growth rate used is typically a forward-looking estimate, often based on analyst projections for the next 3 to 5 years. The P/E ratio may be based on trailing twelve months (TTM) earnings or forward earnings estimates, depending on the methodology.

How to Use This Calculator

Enter the P/E ratio. Use either trailing or forward P/E, but be consistent with your analysis.
Enter the expected earnings growth rate. This should be expressed as a percentage (e.g., 12 for 12% growth).
Click calculate. The tool will return the PEG ratio instantly.

The result helps you compare stocks across different growth rates and valuation levels.

Interpreting PEG Ratio Results

There is no universal rule for what constitutes a "good" PEG ratio, but common benchmarks include:

Below 1.0: May indicate the stock is undervalued relative to its expected growth.
Around 1.0: Suggests the stock is fairly valued based on growth expectations.
Above 1.0: May indicate the stock is overvalued relative to its growth rate.

These benchmarks are general guidelines. Industry norms, market conditions, and the reliability of growth estimates all affect interpretation.

Common Mistakes When Using the PEG Ratio

Using inconsistent time periods. Mixing trailing P/E with forward growth rates can distort results.
Relying on overly optimistic growth estimates. Analyst projections can be inaccurate, especially for volatile sectors.
Ignoring negative earnings. The PEG ratio is not meaningful for companies with negative earnings or negative growth rates.
Applying it to mature or cyclical companies. The PEG ratio works best for companies with predictable, sustainable growth.

Limitations of the PEG Ratio

The PEG ratio is a useful screening tool but has notable limitations:

Growth estimates are uncertain. Future earnings growth is never guaranteed, and small changes in the growth rate can significantly alter the PEG ratio.
Does not account for risk or debt. Two companies with the same PEG ratio may have very different risk profiles or capital structures.
Not suitable for all companies. Companies with negative earnings, declining growth, or irregular earnings patterns produce misleading PEG ratios.
Short-term focus. The PEG ratio typically uses 3-5 year growth estimates, which may not reflect long-term value.

Use the PEG ratio alongside other valuation metrics such as P/E, P/B, and discounted cash flow analysis for a more complete picture.

Practical Use Cases

Screening growth stocks. Quickly identify companies where valuation appears reasonable relative to growth expectations.
Comparing companies within the same sector. The PEG ratio is most useful when comparing similar companies with comparable growth profiles.
Validating investment theses. Use the PEG ratio as a sanity check when evaluating whether a growth stock is priced fairly.

Frequently Asked Questions

What is a good PEG ratio?

A PEG ratio below 1.0 is often considered attractive, suggesting the stock may be undervalued relative to its growth. A ratio around 1.0 suggests fair valuation, while above 1.0 may indicate overvaluation. However, these thresholds vary by industry and market conditions.

Can the PEG ratio be negative?

Yes. A negative PEG ratio occurs when a company has negative earnings (negative P/E) or negative expected earnings growth. In both cases, the PEG ratio is not meaningful for valuation purposes.

What is the difference between P/E and PEG ratio?

The P/E ratio measures current valuation based on earnings. The PEG ratio adjusts the P/E by incorporating expected earnings growth, making it more useful for evaluating growth companies. A high P/E may be justified if the company has strong growth prospects, which the PEG ratio helps assess.

Should I use trailing or forward P/E for the PEG ratio?

Both approaches are used, but consistency matters. Trailing P/E uses historical earnings, while forward P/E uses estimated future earnings. For the PEG ratio, forward P/E is often preferred because it aligns with the forward-looking nature of the growth rate. However, using trailing P/E with forward growth creates a mismatch that can distort results.

Is the PEG ratio reliable for all stocks?

No. The PEG ratio works best for companies with predictable, positive earnings growth. It is less reliable for cyclical companies, companies with negative earnings, or those with highly volatile growth rates. It should be used as one tool among several in a broader valuation analysis.