The PEG ratio adjusts the PE ratio for expected earnings growth. It provides a more complete picture than PE alone by factoring in how fast a company is growing.
A stock with PE of 30 and 15% annual earnings growth: PEG = 30 ÷ 15 = 2.0. A stock with PE 20 and 20% growth: PEG = 20 ÷ 20 = 1.0.
PEG below 1 is generally considered undervalued. PEG of 1 = fair value. PEG above 1 = possibly overvalued. Best for comparing growth stocks in the same sector.
| Stock | Trailing P/E | EPS Growth | PEG | Assessment |
|---|---|---|---|---|
| NVIDIA (NVDA) | 45x | 58–82% | 0.57–0.78 | Potentially undervalued vs. growth |
| Amazon (AMZN) | 33x | 28%+ | 0.62 | Attractive on TTM basis |
| Super Micro (SMCI) | ~15x | 70.6% | 0.34 | Lowest PEG among major growth stocks |
| Apple (AAPL) | 35x | ~10% | ~3.5 | Premium valuation for slower growth |
Data sourced from financial screeners, January 2026. PEG fluctuates daily with price and analyst revisions.
💡 Pro Tip: Compare Within Sectors
PEG is most meaningful when comparing companies in the same industry. A tech stock with PEG 1.5 may be cheap for its sector, while a utility stock with PEG 1.5 could be expensive. Always compare apples to apples.
1. Using trailing growth for a cyclical company. PEG works best with forward growth estimates. A cyclical stock (e.g., semiconductor) may show 80% trailing growth that's about to collapse, making the PEG misleadingly attractive.
2. Ignoring the quality of earnings growth. Growth from share buybacks or one-time tax benefits inflates EPS without real business expansion. Check whether revenue is growing alongside EPS.
3. Treating PEG < 1 as an automatic "buy." A low PEG can signal that the market doubts the growth estimates. Sometimes the crowd is right — always cross-check with fundamentals like debt levels, margins, and competitive moat.
4. Using different time horizons. Mixing a trailing P/E with a 5-year growth forecast creates a meaningless PEG. Make sure both inputs cover the same period — typically the next 1–3 years.
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PEG below 1.0 generally indicates undervaluation — you're paying less for each unit of growth. PEG around 1.0 is fairly valued. Above 1.5 suggests the stock may be expensive relative to its growth rate. Peter Lynch popularized this metric and favored PEGs below 1.0.
Can PEG be negative?
Yes, when earnings growth is negative. A negative PEG is essentially meaningless — it means the company is shrinking, and no P/E ratio makes it a good value in that context. Skip PEG analysis for companies with declining earnings and focus on why earnings are falling.
Which growth rate should I use for PEG?
Use forward (expected) earnings growth, not trailing. The 3-5 year consensus growth estimate from analysts is standard. Using trailing growth can mislead — a company that grew 50% last year but is expected to grow 10% going forward should use 10%, not 50%.
What is a good PEG ratio?
PEG below 1.0 is generally considered undervalued — you're paying less for each unit of growth. PEG around 1.0 is fairly valued. PEG above 1.5 suggests the stock may be overpriced relative to its growth. Peter Lynch popularized this metric, arguing that a company growing at 20% with PE of 20 (PEG = 1.0) is fairly priced.
What are the limitations of PEG ratio?
PEG relies on growth estimates, which are often wrong. It doesn't account for dividends, debt levels, or cash flow. It's also less useful for slow-growth companies (under 5%) or cyclical businesses where earnings fluctuate wildly. Use PEG as a screening tool, not a standalone decision maker.
Forward PEG vs trailing PEG?
Forward PEG uses analyst growth estimates for the next 3-5 years, while trailing PEG uses historical growth. Forward PEG is more relevant for investing (markets care about the future) but relies on estimates that may be inaccurate. Trailing PEG is factual but backward-looking. Check both for a balanced view.