What Is the PEG Ratio?

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 Rate

Two stocks, same P/E of 30×:

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 0.5×.

What "fair value" actually means#

PEG of 1.0 is the traditional benchmark — you are paying exactly one times the growth rate.

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 1,385 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 lower from 1.3× to 1.2×.

579 stocks trade below 1.0× — growth may be underpriced, or the market is doubting the estimates. 288 trade above 3.0× — the multiple has run ahead of earnings growth.

Consumer Defensive has the highest average PEG at 2.4×. Communication Services 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?