The Two Formulas This Tool Uses
P/E Ratio = Share Price ÷ Earnings Per Share. If you only have raw financial statements rather than a published EPS figure, derive it first with EPS = Net Income ÷ Shares Outstanding, then plug that into the P/E formula. The calculator does this automatically when you choose the "Calculate EPS" mode above.
Earnings Yield (%) = (EPS ÷ Share Price) × 100, which is simply the inverse of the P/E ratio expressed as a percentage. It is arguably the more useful of the two numbers for a specific reason: it puts a stock on the same footing as a bond. A P/E of 25 doesn't mean anything to most people intuitively, but an earnings yield of 4% is directly comparable to a 10-year Treasury yield or a savings account rate — you can immediately judge whether you're being compensated for the extra risk of owning the stock.
A Worked Example
Suppose a company reports Net Income of $12,000,000 for the year and has 2,000,000 shares outstanding. Its stock currently trades at $150 per share.
- EPS = $12,000,000 ÷ 2,000,000 shares = $6.00 per share
- P/E Ratio = $150 ÷ $6.00 = 25
- Earnings Yield = ($6.00 ÷ $150) × 100 = 4.0%
Read together, this tells you the market is paying 25 times last year's earnings for this stock, which is equivalent to a 4% earnings yield. Whether that's expensive or cheap depends entirely on what else is available — the same industry's average P/E, this company's own 5-year average P/E, or the yield on a risk-free bond.
Why a P/E Number Alone Can Mislead You
A P/E ratio has no meaning in isolation. A software company with a P/E of 40 might be perfectly reasonably priced relative to its growth rate and industry peers, while a utility company with the same P/E of 40 would look wildly overvalued next to the sector average of 15-18. Earnings themselves can also be temporarily depressed or inflated by one-off items, accounting changes, or a bad quarter, which distorts the ratio without reflecting the business's true earning power. Always compare P/E against a peer group, an industry benchmark, or the company's own historical range — never treat a single P/E number as a verdict by itself.
Frequently Asked Questions
Q: What does a negative P/E ratio mean?
A: It means the company had negative earnings (a net loss) over the period used. A negative P/E isn't meaningful as a valuation multiple, so most data providers simply display it as "N/A" rather than a negative number, which is what this calculator flags too.
Q: Should I use trailing EPS or forward (estimated) EPS?
A: Either is valid as long as you're consistent when comparing companies. Trailing P/E uses the last 12 months of actual reported earnings; forward P/E uses analysts' projected earnings for the next 12 months. Forward P/E is more forward-looking but depends on estimates that can be wrong.
Q: Why is earnings yield more useful than P/E for comparing to bonds?
A: Bond yields are already expressed as a percentage return, so converting a stock's earnings into the same percentage format (via 1 ÷ P/E) lets you compare the two directly on a like-for-like basis, something the raw P/E multiple can't do.
Q: Can I use this for a company with no earnings at all (EPS of zero)?
A: No. Dividing by zero EPS produces an undefined P/E ratio. Early-stage or pre-profit companies are usually valued with other metrics, such as price-to-sales, instead of P/E.
Disclaimer: This calculator is for educational purposes only and does not constitute investment advice. P/E ratios and earnings yield are just two of many valuation tools and should never be used alone to decide whether to buy or sell a stock. Always do your own research or consult a qualified financial advisor before making investment decisions.