Price-to-earnings ratio (P/E): formula, examples and limits

The price-to-earnings ratio, or P/E, is the share price divided by earnings per share. It tells you how many dollars investors are paying for one dollar of a company's annual profit. A P/E of 20 means the market values the company at 20 times what it earned. It is the most widely quoted valuation multiple in the world, printed next to nearly every stock quote.

Its popularity comes from its simplicity: two numbers anyone can find. Its traps come from the same place. The price changes every second, the earnings change four times a year, and the earnings figure can be GAAP or adjusted, last year's or next year's. A single company can have several "correct" P/E ratios on the same day.

This page calculates Apple's P/E at the end of fiscal 2025, turns it into an earnings yield, follows the trailing P/E through two years of report dates, and covers when the ratio breaks down and how to compare it fairly.

The formula

The two forms agree when they use the same share count. The per-share version is the convention because share price and EPS are both published per share. The EPS is almost always diluted EPS; the Earnings per share (EPS): basic vs diluted, with Apple’s numbers page explains why.

What the number means

A P/E is a price, not a verdict. A P/E of 34.2 says investors were paying $34.20 for each dollar Apple earned in fiscal 2025. Whether that is reasonable depends on what they expect the company to earn later, how certain those earnings are, and what else their money could earn.

The earnings yield makes the last point concrete. If Apple paid out every dollar of profit, a buyer at $255.46 would collect 2.9% a year at fiscal 2025's earnings level. That is a yield to set beside a Treasury bond. A buyer accepting it is betting, implicitly, that earnings will grow. Higher expected growth and lower risk both justify a higher P/E; higher interest rates usually pull P/E ratios down across the market.

As a rough rule of thumb, the US large-company market has spent much of its history with an average P/E somewhere in the teens to the twenties, and fast-growing companies trade above the market. Treat any such range as context, not a threshold: there is no P/E at which a stock becomes "cheap" or "expensive" on its own.

Trailing P/E and why it jumps

The P/E most quote screens show is the trailing twelve months (TTM) P/E: today's price divided by the sum of the last four reported quarters of EPS. The price moves daily, but the denominator changes only when a company reports. On each report day, a new quarter enters the sum and the same quarter from a year earlier leaves it.

Two things stand out. First, the end-of-year P/E depends on whether the year has been reported. On September 26, 2025, an investor could only see the last four reported quarters, which still included Q4 fiscal 2024; the trailing P/E was 38.8. The 34.2 at the top of this page uses fiscal 2025 EPS that Apple did not publish until October 30. Both numbers are correct; they answer different questions.

Second, the fiscal 2024 tax charge distorted the trailing P/E for a full year. Q4 fiscal 2024's $0.97 was depressed by the one-time $10.2 billion State Aid charge (about $0.67 a share). While that quarter was in the trailing sum, from October 31, 2024 to October 29, 2025, trailing EPS was lower and the P/E higher than the underlying business justified. When the quarter rolled out on October 30, 2025, TTM EPS jumped from $6.59 to $7.47, a 13% step, and the P/E fell from 40.9 to 36.3 in a day while the price barely moved. The chart switches to the new EPS on the release day itself, even though Apple reports after the close, so each step lands one session before the market could trade on the news.

The lesson: a P/E chart mixes two signals, the price and the earnings. Before reading a change in P/E as investors becoming more or less optimistic, check whether the denominator moved. Between January 29 and July 30, 2026, Apple's P/E rose from 32.7 to 38.2 while EPS rose too; that rise was the price, up 29%.

Trailing versus forward

A forward P/E divides today's price by EPS expected over the next twelve months or the next fiscal year, using analysts' consensus estimates. It looks at the earnings an investor is actually buying, at the cost of relying on forecasts. The Forward P/E ratio: valuing a stock on expected earnings page covers how it is built and how wrong estimates can be; for Apple at the end of fiscal 2025 the answer ranged from 29.3 to 42.0 depending on the earnings figure used. Dividing P/E by the growth rate gives the PEG ratio: adjusting the P/E for earnings growth.

When P/E misleads

Negative or tiny earnings. A company that lost money has no meaningful P/E; most sites show "N/A" or a dash. Earnings close to zero produce enormous ratios (a stock at $50 with EPS of $0.10 has a P/E of 500) that tell you only that profits are depressed. For such companies, price-to-sales or EV/EBITDA is usually more useful.

Cyclical companies. Carmakers, chipmakers, steel and energy companies earn the most at the top of their cycle and the least at the bottom. Their P/E is often lowest at peak earnings, just before profits fall, and highest at the trough, just before they recover. A low P/E on a cyclical can be a warning rather than a bargain. Analysts often use average earnings over a full cycle instead.

One-time items. As Apple's tax charge shows, a single unusual quarter can move trailing EPS for a year. Read the reconciliation in the GAAP vs non-GAAP earnings: how adjusted numbers are built page's sense before trusting a sudden change.

Leverage and cash. P/E uses equity value and profit after interest, so two companies with the same business and different debt levels can have different P/Es. Apple held $132.4 billion of cash and marketable securities against $98.7 billion of debt at the end of fiscal 2025; enterprise-value multiples such as EV/EBITDA adjust for that.

Buybacks and accounting choices. Shrinking share counts lift EPS and lower P/E without the business changing; different depreciation or revenue policies change earnings too.

Comparing P/E ratios

P/E is most useful as a comparison, but only between like and like. Use the same EPS basis (GAAP or adjusted, trailing or forward), the same date for prices, and companies with similar businesses, growth and risk. The Comparable company analysis: how to build and read a comps table page builds a full comps table; here are three large technology companies priced on March 31, 2026 on their latest fiscal-year GAAP diluted EPS:

The fiscal years end on different dates: Microsoft's was nine months old on March 31, 2026, Alphabet's three months. A strict comparison would use the same twelve-month window for all three. A higher P/E for Apple says the market priced its earnings at a higher multiple on that day. It does not say why, and it does not say which is the better investment.

P/E and its neighbours

How Finabase does it

The summary page at /symbol/aapl shows P/E and Forward P/E in the header strip and Trailing P/E, Forward P/E, PEG ratio and EPS (TTM) in its key statistics. These values come from the data provider on a trailing-twelve-month basis; Finabase passes them through rather than computing them, so they can differ by a few tenths from your own calculation depending on the provider's EPS figure and price time.

The Valuation tab charts the P/E for each of the last ten fiscal years (fiscal-year data, annual only), useful for seeing where a company's multiple sits against its own history. The screener can filter stocks by P/E Ratio, and the Financials tab has the quarterly diluted EPS to build a TTM sum yourself.

Frequently asked questions

What is a good P/E ratio?

There is no single good number. A P/E reflects expected growth, risk and interest rates, so it is only meaningful against the company's own history, its peers and the market. A low P/E can mean an opportunity or a business in decline.

What is the difference between trailing and forward P/E?

Trailing P/E divides the price by the last four quarters of reported EPS; forward P/E divides it by analysts' estimated EPS for the next twelve months or fiscal year. Trailing is factual but backward-looking; forward is relevant but only as good as the estimates.

Why did Apple's P/E change when the price didn't?

Because the earnings in the denominator changed. When Apple reported on October 30, 2025, a weak quarter that included a one-time tax charge left the trailing sum, EPS rose 13% and the P/E fell from 40.9 to 36.3 in one day.

What does a negative P/E mean?

It means the company lost money over the period. A negative P/E has no useful interpretation, so most data sources show it as not meaningful.

Summary

The P/E ratio divides the share price by earnings per share: Apple's was $255.46 ÷ $7.46 = 34.2 at the end of fiscal 2025, an earnings yield of 2.9%. The trailing P/E changes with the price every day and with the earnings on every report day, which is why Apple's fell from 40.9 to 36.3 on October 30, 2025 when a tax-depressed quarter dropped out, and why it stood at 40.0 on $8.72 of TTM EPS on October 29, 2026. Use P/E against a company's own history and close peers on the same basis, and switch to other multiples when earnings are negative, cyclical or distorted by one-off items.