PEG Ratio Calculator
Calculate Price/Earnings to Growth (PEG) ratio — P/E divided by growth rate. PEG accounts for growth and gives a more nuanced valuation than P/E alone, popular with Peter Lynch investors.
This free online peg ratio calculator provides instant results with no signup required. All calculations run directly in your browser — your data is never sent to a server. Enter your values below and see results update in real time as you type. Perfect for everyday calculations, homework, or professional use.
How to Use This Calculator
Enter your input values
Fill in all required input fields for the PEG Ratio Calculator. Most fields include unit selectors so you can work in your preferred unit system — metric or imperial, whichever matches your problem.
Review your inputs
Double-check that all values are correct and that you have selected the right units for each field. Incorrect units are the most common source of calculation errors and can produce results that are off by factors of 2, 10, or more.
Read the results
The PEG Ratio Calculator instantly computes the output and displays results with units clearly labeled. All calculations happen in your browser — no loading time and no data sent to a server.
Explore parameter sensitivity
Try adjusting individual input values to see how the output changes. This is a quick and effective way to develop intuition about how different parameters influence the result and to identify which inputs have the largest effect.
Formula Reference
PEG Ratio Calculator Formula
See calculator inputs for the governing equation
Variables: All variables and their units are labeled in the calculator interface above. Input fields accept values in multiple unit systems — select your preferred unit from the dropdown next to each field.
When to Use This Calculator
- •Use the PEG Ratio Calculator when comparing financial options side-by-side — such as different loan terms or investment returns — to make more informed decisions.
- •Use it to quickly estimate costs or returns before making purchasing, investment, or borrowing decisions.
- •Use it for financial education and planning to understand how compound interest, fees, or tax affects the real value of money over time.
- •Use it when building or reviewing a budget to verify that projections and calculations are mathematically correct.
About This Calculator
The PEG Ratio Calculator is a free financial calculation tool designed to help individuals and businesses understand key financial concepts and estimate costs, returns, and loan parameters. Calculate Price/Earnings to Growth (PEG) ratio — P/E divided by growth rate. PEG accounts for growth and gives a more nuanced valuation than P/E alone, popular with Peter Lynch investors. The calculations are based on standard financial mathematics formulas. Results are for informational and educational purposes only and should not be considered financial, investment, or tax advice. Consult a qualified financial professional before making financial decisions. All calculations are performed in your browser — no personal financial data is stored or transmitted.
About PEG Ratio Calculator
The PEG Ratio Calculator computes Peter Lynch's famous Price/Earnings-to-Growth metric, which adjusts the P/E ratio for a company's growth rate. The core insight: a company growing earnings at 30% per year deserves a higher P/E than one growing at 5%. PEG captures this by dividing P/E by growth rate. A PEG of 1.0 is considered 'fair' value — the P/E matches the growth rate. Below 1.0 suggests undervaluation, above 1.0 suggests overvaluation. PEG is especially useful for growth stocks where traditional P/E can look expensive but might actually be reasonable given growth.
The Math Behind It
Formula Reference
PEG Formula
PEG = P/E Ratio / Annual Earnings Growth Rate
Variables: Growth rate expressed as a percentage (e.g., 20 for 20%)
Worked Examples
Example 1: Growth Stock at Fair Value
A company has a P/E of 25 and expected 25% annual earnings growth.
PEG of 1.0 — fair value per Lynch's framework. The premium P/E is justified by the strong growth.
Example 2: Expensive Growth Stock
A tech darling has P/E of 80 with 20% projected growth.
PEG of 4.0 — significantly overvalued. Much of the market price assumes growth exceeding the projection.
Common Mistakes & Tips
- !Using unrealistic growth estimates. Analyst projections are often too optimistic, especially for small caps.
- !Ignoring the quality of earnings growth. PEG doesn't distinguish between high-quality recurring growth and one-time boosts.
- !Comparing PEG across industries without adjustment. Some industries justify higher PEGs.
- !Using the wrong P/E — trailing, forward, or GAAP? Be consistent.
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Frequently Asked Questions
Who invented the PEG ratio?
Peter Lynch popularized PEG in his 1989 book 'One Up On Wall Street', though earlier academics had proposed similar metrics. Lynch used it as his primary screening tool while running Fidelity's Magellan Fund, which delivered 29% annual returns from 1977-1990.
What's a good PEG ratio?
Peter Lynch considered PEG below 1.0 a good value. Below 0.5 is exceptional but rare. Above 2.0 is considered expensive. However, the right PEG depends on the industry — high-quality growers often trade at PEGs of 1.5-2.0, which can still be worthwhile investments.
Can PEG be negative?
Yes, if earnings are declining (negative growth) or the P/E is negative (losses). In both cases, PEG becomes meaningless — you can't value a shrinking company using this metric. PEG only works for profitable, growing companies.
What's dividend-adjusted PEG?
PEGY = P/E / (Growth Rate + Dividend Yield). This accounts for total shareholder return including dividends. A dividend-paying stock with 10% growth and 3% yield has PEGY based on 13% total return. Below 1.0 is considered attractive.