PEG Ratio Calculator 2026

A PEG (Price/Earnings to Growth) ratio calculator evaluates whether a stock is overvalued, undervalued, or fairly valued by comparing its P/E ratio to its earnings growth rate. It's a more refined valuation metric than P/E alone because it accounts for how fast a company is growing. This is useful for growth investors and value investors alike who want to compare stocks with very different growth rates on a level footing.

General guidelines: PEG below 0.5 suggests a very undervalued stock (potential bargain, though worth double-checking); PEG 0.5-1.0 suggests attractive value; PEG around 1.0 suggests fair value; PEG 1.0-2.0 suggests the stock may be overvalued relative to its growth; PEG above 2.0 suggests significant overvaluation. These are guidelines, not hard rules — a low PEG isn't automatically a buy signal if the growth estimate behind it is unreliable.

Forward PEG uses forward P/E (based on estimated future earnings) and projected future growth — it looks ahead but relies on analyst estimates that are often optimistic. Trailing PEG uses trailing P/E (based on the past 12 months' earnings) and historical growth — it's backward-looking but based on actual, verified numbers. Check both, and be appropriately skeptical of forward estimates.

Yes — if earnings growth is negative, meaning the company's earnings are shrinking. For example, a P/E of 20 with -5% growth gives a PEG of -4.0. A negative PEG is generally a warning sign of declining earnings, not a buying signal, though in rare turnaround situations it may reflect a temporary dip rather than a structural decline. Always investigate why growth is negative before drawing conclusions.

You can't — PEG requires a meaningful P/E ratio, and P/E is undefined (or nonsensical) when earnings are negative. For unprofitable companies, use alternative valuation metrics instead, such as Price-to-Sales (P/S) or EV/EBITDA, or wait until the company turns profitable and a trailing P/E becomes available. PEG is designed specifically for comparing profitable, growing companies.