How do you really calculate PEG in practice? Peter Lynch’s go-to valuation shortcut

Peter Lynch popularized the PEG ratio as a quick, practical way to sanity-check whether a stock’s valuation makes sense relative to its growth. Simple in theory. Messy in practice. So here’s the question. When you calculate **PEG**, what do you actually use? **A)** LTM P/E ÷ last year’s revenue growth **B)** NTM P/E ÷ next 12-month EPS growth estimate **C)** LTM P/E ÷ last 3–5 year EPS CAGR **D)** NTM P/E ÷ forward 3–5 year EPS CAGR Which one do you use in practice? There’s no single right answer here. I’m more interested in how people actually calculate PEG and the reasoning behind it.