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What Is the PEG Ratio: P/E That Accounts for Growth

The PEG ratio compares P/E with earnings growth, giving a fairer read on growth stocks than P/E alone. We explain how to calculate it, how to read it, and its limits.

PEGValuationFundamental AnalysisGrowth Stocks

When a high P/E is not really expensive

A stock with a P/E of 40 looks very expensive next to one at 10. But if the first company grows earnings 40% per year while the second grows only 5%, the P/E of 40 may actually be the better deal. The PEG ratio exists to handle exactly this: it places P/E next to the growth rate.

How to calculate PEG

PEG = P/E divided by EPS growth rate (% per year)

Example: a stock has P/E = 30 and earnings (EPS) expected to grow 30% per year, so PEG = 30 / 30 = 1.0.

Another stock has P/E = 15 but grows only 5% per year, so PEG = 15 / 5 = 3.0 — actually "more expensive" in growth-adjusted terms.

How to read PEG

The common convention (popularized by Peter Lynch):

  • PEG near 1: fairly priced — P/E matches growth.
  • PEG below 1: potentially cheap relative to growth — worth a closer look.
  • PEG above 1: potentially expensive — the market is paying more than growth justifies.

PEG is especially useful for growth stocks, where a high P/E is normal and P/E alone would mislead.

Limits to remember

  • Depends on growth projections: the denominator is future growth, which is only an estimate. Wrong growth forecast, wrong PEG.
  • Does not work for low or negative growth: a small or negative denominator makes PEG meaningless.
  • Ignores growth quality: growth from debt or share dilution is not the same as growth from the core business.
  • Excludes dividends: for high-dividend stocks, a PEGY variant adds dividend yield to the denominator.

Using PEG correctly

PEG is a quick screen, not a final verdict. You should:

  • Cross-check against intrinsic value and other multiples like EV/EBITDA.
  • Check whether the growth is sustainable (does the business have an economic moat).
  • Use multi-year growth rather than a single explosive quarter.

Conclusion

PEG is P/E divided by the earnings growth rate, allowing fairer comparison of stocks with different growth. PEG near 1 is reasonable, below 1 may be cheap, above 1 may be expensive. But it is only as good as the growth forecast — use it alongside other measures, not on its own.

Next step

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