PEG: the missing piece in every P/E conversation.
One number that captures both what you pay and how fast earnings grow
Two stocks, two P/Es — only one was actually expensive
Rajan looked at two stocks. One traded at 40 times earnings — he crossed it off immediately. The other at 20 times — he bought it confidently. Six months later, the expensive-looking stock had risen 60%. His cheap one had barely moved. He had done everything right except ask one question: what was each company's growth rate? The P/E had shown him the price. It had shown him nothing about the value.
The P/E ratio tells you how much you're paying for today's earnings. It says nothing about tomorrow's.
A business growing earnings at 40% a year looks completely different from one growing at 5% — even if both trade at the same P/E multiple. Same number, two entirely different realities.
The PEG ratio puts both pieces together. Divide the P/E by the company's annual earnings growth rate. Peter Lynch popularised this in One Up on Wall Street in 1989. His benchmark: a PEG at or below 1.0 suggests the stock may be fairly priced for its growth rate. A PEG above 2 suggests the market has already priced in most of the expected growth. High-quality Indian compounders often trade in the 1-to-2 range — not cheap in the old-school sense, but the growth is the argument.
The tricky part is always the growth rate you use. Historical earnings CAGR? Analyst forecast? A three-year figure from a period the business has already outgrown? The formula is simple arithmetic. Choosing the right input is judgment — and that judgment is where most investors cut corners.
Two kirana shops, two very different deals
One kirana shop earns ₹1 lakh a year. The owner wants ₹20 lakh — a P/E of 20. Down the lane, a second shop also earns ₹1 lakh right now. But regulars are multiplying, a second counter just opened, and earnings are set to double next year. That owner wants ₹40 lakh. P/E 40 looks expensive until you realise you might be paying today's multiple for twice the earnings in twelve months. The PEG ratio is your tool for deciding which shop is the real deal.
Why this matters
Every time you check a stock's P/E, follow it with one more question: what growth rate is this multiple assuming? PEG makes the hidden assumption visible. A 30x P/E on a company growing at 30% is a completely different position from a 30x P/E on one growing at 8%. You're not just paying for earnings — you're paying for a belief about the future. PEG forces that belief into the open so you can examine it. Think of it as a screening question, not a verdict. It takes ten seconds and tells you whether to investigate further or move on.
Enter a P/E. See exactly what growth the price demands.
Enter your stock's current P/E in the box below. The widget shows the exact annual earnings growth rate needed to bring PEG to 1.0 — then you compare that number against the company's actual track record.
What growth rate is this P/E actually asking for?
A P/E of 30x requires 30% annual EPS growth for a fair PEG of 1.0. With historical growth at 15%, the current PEG is 2x. Higher PEG means paying a premium over past growth. Past growth is just a reference, not a guarantee. PEG is only as accurate as your future growth estimate.
PEG is a question — not an answer
Where people go wrong
- Using stale growth from a faster eraA company that grew at 35% for three years may now be maturing. Using that old CAGR as the PEG denominator flatters the ratio and makes the stock look cheaper than it is.
- Comparing PEG across different sectorsA PEG of 1.5 in pharma and a PEG of 1.5 in fintech carry very different risk profiles. Cross-sector PEG comparisons mislead more than they clarify.
- Ignoring debt when PEG looks lowBorrowed capital can inflate near-term EPS without improving the underlying business. A leveraged company's PEG can look attractive while the balance sheet carries real risk.
- Treating PEG below 1 as an automatic buyPEG below 1 is a reason to investigate, not a reason to act. The first question is always whether the growth rate in the denominator is still achievable.
PEG divides P/E by earnings growth — it shows what you pay per unit of growth, not just per unit of today's earnings.
Lynch's benchmark: PEG at or below 1.0 suggests fair pricing; above 2 means growth is likely already baked into the price.
The growth rate is the dangerous input — always verify whether it's historical, analyst-forecast, and still realistic for this business.
PEG feels like it settles the growth-versus-value debate in a single step. That comfort is exactly the danger — most investors stop there and forget to ask whether the growth rate they plugged in was real.