Divide share price by earnings per share for the P/E ratio — the most common stock valuation multiple — plus the earnings yield.
P/E = price ÷ earnings per share — what investors pay for each dollar of annual earnings. Earnings yield is its inverse (EPS ÷ price). PEG divides P/E by growth rate to judge whether a high P/E is justified (near 1 is often seen as fair). P/E only works with positive earnings, and varies hugely by sector. Not investment advice.
The P/E ratio is the headline valuation multiple: a P/E of 20 means investors pay $20 for each $1 of annual earnings. High P/Es price in growth expectations; low ones can signal value — or trouble. The earnings yield (the inverse) lets you compare a stock to bond yields, and PEG adjusts P/E for growth.
P/E = price ÷ EPS · Earnings yield = EPS ÷ price
The P/E ratio answers one narrow question: how many dollars of share price am I paying for one dollar of annual earnings? That is all it is. It is not a measure of quality, of safety, or of whether a company is growing — it is a price tag expressed in units of profit. The reason it is the most-quoted multiple in investing is that it normalises for share count: a $30 stock and a $3,000 stock are not comparable, but 18× earnings and 40× earnings are, at least inside the same industry.
Take the numbers the calculator loads with: a share price of $150 and earnings per share of $6. Divide and you get a P/E of 25. Read it as a sentence and it becomes useful: investors are paying $25 today for each $1 the company earns in a year, so at today's profit level it would take 25 years of earnings to repay the price. Flip the fraction and you get the earnings yield — $6 ÷ $150 = 4% — which is the form that lets you compare a stock against a bond or a savings rate directly, because it is denominated the same way. A 4% earnings yield and a 4% bond coupon are the same first number; what differs is that the bond's 4% is contractual and the company's 4% can grow, shrink or vanish.
The third default — 12% expected EPS growth — produces the PEG: 25 ÷ 12 = 2.08. The rough convention is that a PEG near 1 means the multiple is roughly in line with growth, so 2.08 says the price already assumes a good deal more than 12%. Run it backwards and the arithmetic is blunt: for that P/E of 25 to sit at a PEG of 1, earnings would need to compound at 25% a year. Alternatively, hold the price still and let EPS rise from $6 to $7.50 — a 25% jump — and the P/E falls to 20 on its own. That is the whole mechanism of a growth stock: the multiple is a bet that the denominator moves.
Useful rules of thumb, all of them soft. Compare a P/E only against the same company's own history and against direct competitors, never against a market-wide average — software, utilities and banks trade in different bands for structural reasons, and a "cheap" bank at 10× is not cheap relative to banks. Decide whether you are looking at a trailing P/E (last twelve months, a fact) or a forward P/E (next twelve months, an estimate) and never mix the two in the same comparison; the forward figure is almost always the lower one because it embeds growth that has not happened. And treat a very low P/E as a question rather than an answer: the market usually prices earnings low because it expects them to fall, which is the classic value trap.
The first is using EPS uncritically. Reported earnings include one-off items — an asset sale, a legal settlement, a writedown — and a single good quarter can halve a P/E without anything improving. The second is ignoring the balance sheet: P/E says nothing about debt, so two companies at 25× are not equivalent if one is financed with borrowings and the other has net cash. The third is the negative-earnings case, which this calculator refuses to answer rather than printing a number — a P/E computed on a loss is meaningless, not "very high." The fourth is treating the earnings yield as though it were income: 4% is the company's profit per dollar of your price, not a cheque that arrives — for what is actually paid out, the dividend yield calculator is the right tool. And if you want to know whether the earnings behind the multiple are being generated efficiently rather than simply being large, the return on equity calculator answers that question.
A ratio is a snapshot of one company on one day. What actually changes decisions is the series: the same multiple for the same holdings recorded quarter after quarter, so you can see whether you bought a re-rating or a real improvement in earnings. That is a log, not a calculation, and it is also where cost basis, position size and dividends received have to live. Our investment portfolio tracker keeps holdings, cost basis and valuation in one sheet. None of this is investment advice — it is arithmetic you can check.
No — it can mean the market expects earnings to fall (a "value trap"). Read P/E alongside growth (PEG), debt, and the industry norm, not in isolation.
P/E divided by the earnings growth rate. A PEG near 1 suggests the valuation is roughly in line with growth; well below 1 can indicate an undervalued grower.
Related: return on equity calculator · dividend yield calculator · real rate of return calculator · all free calculators.
More free business metrics tools — no signup, works on any device.
Yes. The P/E Ratio Calculator is completely free, runs in your browser, and never asks for a signup, email, or download. Enter your numbers and the result updates instantly.
It uses standard formulas and recalculates the moment you change a value, so the math is exact for the inputs you enter. Treat the result as a reliable planning estimate; for decisions with legal or tax consequences, confirm the figures with a qualified professional.
Yes. The calculator is mobile-friendly and works on any phone, tablet, or computer — there is no app to install and nothing to save.
Yes. Scroll to “Add this free calculator to your site” above and copy the embed snippet to place the live calculator on your blog or website for free.
Last reviewed: September 2026. Free to use, no signup — P/E Ratio Calculator by ToolWise Digital.
Copy the snippet to embed the live calculator on your blog or website — free for any site. The small “Calculator by ToolWise Digital” credit line keeps it free; you're welcome to remove it, but we appreciate you leaving it.
Ready-made Google Sheets & Excel trackers for money, taxes, and small business — each with a free phone version.
Browse the shop →Simple Monthly Budget and our Small Business Bookkeeping template (Google Sheets & Excel) — no signup, no wall, just the files. If you also want the occasional short note on pricing, bookkeeping and the money side of a small business, the list is here. No spam — unsubscribe anytime.