# PEG Ratio: Relating P/E to Earnings Growth

The PEG ratio divides a consistently defined P/E by an earnings-growth percentage; it is highly sensitive to forecast horizon, growth units, EPS quality, cyclicality, and risk.

Canonical: https://wiki.fcontext.com/stocks/peg-ratio/
Fact checked: 2026-07-21

> For educational purposes only; not investment advice.

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## Direct answer

The **PEG ratio** divides a price-to-earnings ratio by an earnings-growth rate expressed as a percentage number:

`PEG = P/E ÷ EPS growth rate (%)`

If forward P/E is `30` and the expected annual EPS growth rate is `20%`, convention enters growth as `20`, producing `PEG = 30 ÷ 20 = 1.5`. Entering `0.20` would produce a value 100 times too large under this convention.

PEG is not a GAAP measure and has no universal definition. A result is interpretable only when the earnings basis, growth measure, forecast horizon, units, and data date are stated. “PEG below 1 is cheap” is a shortcut, not a valuation law.

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## Match the numerator and denominator

A defensible calculation pairs comparable inputs:

- **Forward P/E** should use a forward EPS growth forecast covering a clearly stated horizon.
- **Trailing P/E** paired with historical growth describes the past and should not be presented as a forward valuation.
- Growth can mean next-year growth, a two- or five-year CAGR, or an analyst's long-term forecast. These are not interchangeable.
- GAAP EPS and adjusted EPS can produce very different P/E and growth rates. Reconcile stock compensation, restructuring, acquisition costs, amortization, tax items, and share-count assumptions.
- Use per-share growth rather than total net-income growth when dilution or buybacks are material.

PEG compresses valuation and growth into one number but omits the duration of growth, reinvestment required to produce it, return on incremental capital, balance-sheet risk, cash conversion, cyclicality, and discount rate. Two companies with the same PEG can have very different economics.

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## Sensitivity to one forecast

A stock trades at `$60` and expected next-year EPS is `$2`, so forward P/E is `30`. Analysts expect EPS to grow from `$2.00` to `$3.46` over three years:

`EPS CAGR = ($3.46 ÷ $2.00)^(1/3) - 1 ≈ 20%`

`PEG = 30 ÷ 20 = 1.5`

Now vary only the growth estimate:

| Expected EPS CAGR | PEG |
| ---: | ---: |
| 25% | 1.2 |
| 20% | 1.5 |
| 15% | 2.0 |
| 10% | 3.0 |

The market price and P/E did not change, yet the apparent conclusion changed sharply. If EPS starts at a depressed `$0.50` and rebounds to `$2.00`, the unusually high growth rate can make PEG look low even though earnings merely normalized. If EPS is zero, negative, or expected to decline, PEG is generally not economically meaningful.

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## Use checklist

- Record price date, fiscal periods, consensus timestamp, P/E type, EPS definition, growth horizon, and whether growth is a CAGR.
- Recalculate EPS from filings and reconcile analyst or company adjusted measures to GAAP.
- Test multiple growth paths, including margin normalization, dilution, recession, and a fade toward mature growth.
- Ask how much capital is required. Growth that consumes more cash than it creates is not equivalent to capital-light growth.
- Compare businesses with similar accounting, cyclicality, leverage, margins, and reinvestment economics.
- Examine free cash flow per share and return on incremental invested capital alongside EPS.
- Avoid PEG for loss-making firms, unstable denominators, early turnarounds, commodity peaks and troughs, or one-time tax effects.
- Use a cash-flow valuation or scenario analysis to test whether price is justified after growth slows.

PEG may be a compact comparison tool for profitable companies with reasonably stable, comparable growth, but it should remain an input rather than a target price method.

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## Common misconceptions

- “PEG of 1 is fair value.” The threshold ignores risk, interest rates, growth duration, capital intensity, and accounting quality.
- “Lower PEG is always better.” A low value can reflect cyclical peak earnings, a weak forecast, leverage, or expected deterioration.
- “Growth means revenue growth.” Standard PEG normally uses EPS growth; revenue and EPS can diverge through margins and share count.
- “Any two published PEG values are comparable.” Providers can use different P/E bases, EPS adjustments, horizons, and growth forecasts.
- “A negative PEG is attractive.” Negative earnings or growth usually makes the ratio uninterpretable.
- “PEG captures dividends.” The basic formula does not; modified variants must be clearly labeled and cannot be mixed with standard PEG.

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## Related topics

- [Price-to-Earnings Ratio](/stocks/pe-ratio/)
- [Earnings per Share](/stocks/eps/)
- [Earnings Quality](/stocks/earnings-quality/)

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## Authoritative sources

- [PE Ratios, PEG Ratios, and Estimating the Implied Expected Rate of Return on Equity Capital](https://doi.org/10.2308/accr.2004.79.1.73) - Peter D. Easton, *The Accounting Review* (2004)
- [Beginners' Guide to Financial Statements](https://www.sec.gov/about/reports-publications/investorpubsbegfinstmtguide) - SEC
- [Non-GAAP Financial Measures](https://www.sec.gov/corpfin/non-gaap-financial-measures.htm) - SEC