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P/E tells you the price. PEG tells you whether the price makes sense for how fast the company is growing.
That is the entire ratio in one sentence.
The formula#
PEG Ratio = P/E Ratio ÷ Annual EPS Growth RateTwo stocks, same P/E of 30×:
| Stock | P/E | Growth Rate | PEG | Verdict |
|---|---|---|---|---|
| Company A | 30× | 30% | 1.0× | Fair value |
| Company B | 30× | 10% | 3.0× | You're paying 3× the growth rate |
Peter Lynch's rule of thumb: PEG below 1.0 = potentially undervalued. Above 2.0 = the multiple has outrun the growth.
Why P/E alone misleads you#
In 2022, NVIDIA traded at a P/E that looked absurd — 50×, 60×, higher. Investors who stopped at P/E called it expensive and moved on.
They missed the other half of the equation.
Earnings growth estimates were running at 100%+. That put the PEG below 1.0 — the stock was growth-adjusted cheap even while the headline multiple looked stretched. The investors who understood PEG held. The ones who used P/E alone did not.
That is the whole point of the ratio. Today, NVIDIA Corporation (NVDA) trades at a PEG of 0.4×.
What "fair value" actually means#
PEG of 1.0 is the traditional benchmark — you are paying exactly one times the growth rate.
| PEG | What it signals |
|---|---|
| Below 0.5× | Growth may be underpriced — or the market does not believe the estimates |
| 0.5× – 1.5× | Reasonable range for a growing business |
| Above 2.0× | P/E has run ahead of growth; premium must be justified |
| Above 3.0× | Priced for near-perfect execution; any earnings miss re-rates fast |
Where PEG actually works#
PEG works best on companies growing 10%–40% annually. At the extremes:
- Slow-growth businesses (utilities, REITs, staples): a 3% grower at 15× P/E shows PEG of 5.0 — looks expensive, but 15× is cheap for a steady compounder.
- Hypergrowth (100%+ growth): PEG looks artificially cheap; the real question is whether that growth holds — which PEG cannot answer.
Current market context#
Across 1,403 large US companies with positive earnings and a valid growth estimate, the cap-weighted PEG sits at 1.3× today.
Over the last 35 days, it has moved higher from 1.2× to 1.2×.
584 stocks trade below 1.0× — growth may be underpriced, or the market is doubting the estimates. 300 trade above 3.0× — the multiple has run ahead of earnings growth.
Healthcare has the highest average PEG at 2.5×. Energy sits at the low end.
Where PEG breaks#
Growth estimates are forecasts, not facts. In 2021, high-multiple tech stocks showed PEGs of 1.5–2.0× on forward estimates — then estimates were cut 40–50% and those same stocks re-rated to 5–8×. Always stress-test: what does PEG look like if growth comes in at half?
Buybacks can fake EPS growth. A company can shrink revenue, cut capex, and buy back 15% of shares — EPS grows, PEG looks attractive. Check whether growth is coming from revenue expansion or a shrinking share count.
Single-year rebounds distort the denominator. One bad year followed by a return to normal looks like 100% EPS growth. Use 3–5 year average rates, not single-year comparisons.
Does not work for unprofitable companies. No earnings = no P/E = no PEG. Use Price to Sales or EV/Revenue instead.
How to use it#
- Use PEG as a tiebreaker, not a screener. Two similar businesses in the same sector — one at 1.2×, one at 2.8× — that gap matters. Screening thousands of stocks on PEG alone surfaces value traps.
- Always check which growth estimate is being used — trailing 12-month, forward 1-year, and 3-year consensus can produce meaningfully different PEGs for the same stock.
- Pair it with margin direction. A company growing EPS 25% while gross margins expand is different from one growing EPS 25% while margins compress. PEG treats them identically; you should not.
- Cross-check with free cash flow. EPS can be managed. FCF is harder to fake. A low-PEG stock where earnings growth is not reflected in FCF growth deserves skepticism.
- The GARP Stocks screen is built on this logic: reasonable PEG plus above-average growth.
Bottom line#
PEG is a lens, not a verdict.
A stock at 0.7× can still disappoint if the growth does not materialize. A stock at 2.5× can still be worth owning if the business has genuine pricing power and the growth rate holds.
What PEG does is force the question P/E alone never asks: are you paying for growth you are actually getting?