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What Is the PEG Ratio — When P/E Alone Isn't Enough

A multiple that fixes P/E's biggest blind spot: it factors in growth rate too, not just the current price relative to earnings.

The definition and formula

PEG (Price/Earnings-to-Growth) is a stock's P/E ratio divided by its expected earnings growth rate (as a percentage). For example, a stock with a P/E of 20 and expected earnings growth of 20% a year gets a PEG of 1.0. A PEG value around 1.0 is traditionally considered 'fair' — the price roughly matches the growth rate.

The problem PEG solves

A P/E ratio alone doesn't distinguish between a fast-growing company and a static one — both can trade at the same multiple, but they aren't equivalent at all. PEG normalizes for that: a company with a high P/E but higher growth can get a lower PEG (relatively cheaper) than a company with a low P/E but slow growth.

The limitation: it depends on a forecast

PEG's weakness is that it relies on a future growth forecast — a forecast, not a fact. Analyst forecasts change, and are sometimes wrong. PEG is calculated from an assumption that can turn out to be inaccurate, so it's important to examine the quality of the growth forecast behind the number, not just the final result.

How StockIQ uses this

StockIQ checks Growth (15% of the score) and Fair Value (another 15%) as two explicitly separate categories — instead of compressing them into a single PEG multiple — to give the user full transparency into each component individually.

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