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Outbyte PC Repair FREEClear out junk files and repair common Windows errorsFree Scan →Outbyte Driver Updater FREEScan for outdated or missing drivers - takes under a minuteDriver Scan →The Shiller CAPE ratio helps you compare the S&P 500’s current price with a decade of inflation-adjusted earnings. Use it as long-horizon valuation context—not as a forecast of when stocks will rise, fall, or crash. To interpret a reading responsibly, check its date and calculation, compare it with other valuation measures and interest-rate conditions, and avoid treating a historical average as a fair-value target.
What the Shiller CAPE ratio measures
CAPE stands for cyclically adjusted price-to-earnings ratio. It is also known as the Shiller P/E or P/E10. In the familiar S&P 500 series, the ratio divides the index’s current price by the average of the previous ten years of earnings, adjusted for inflation. The longer earnings window reduces the influence of any single year’s unusually high or low earnings.
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In simplified form, the calculation is: current index price ÷ average of the previous ten years of inflation-adjusted earnings. The inflation adjustment puts earnings from different years into comparable dollar terms. Multpl’s FAQ describes converting each of those ten years of S&P 500 earnings into current dollars using the Consumer Price Index (CPI), averaging the adjusted figures, and dividing the current index price by that average. Multpl’s Shiller P/E FAQ explains its calculation. Robert Shiller’s Yale data page documents the historical price, earnings, dividend, and CPI data behind the series.
Multpl summarizes its measure this way: “The figures on multpl.com are the PE10 or Shiller PE. They are the price to average earnings from the past ten years.” This is a statement from Multpl’s FAQ, not a quote or endorsement from Shiller or Yale. Multpl also states that “Neither Dr Shiller nor Yale has any affiliation with multpl.com.” Shiller’s Yale page is the official documentation for his historical data; Multpl is a separate provider displaying a series and chart.
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CAPE is a valuation ratio, not a direct estimate of fair value. A higher reading means investors are paying more for each unit of the ten-year inflation-adjusted earnings average. The ratio alone cannot tell you whether earnings will grow, prices will fall, or when either might happen.
How to evaluate a CAPE reading
- Identify the series and observation date. Record the source and date of the reading. Shiller’s historical series, a third-party chart, and a variant such as total-return CAPE may use different construction choices. Because the price component changes frequently and historical presentations may be revised, a number without a date is incomplete. Preserve the provider’s label and date when you note a figure; do not assume that two charts show the same observation simply because both call it “CAPE.”
- Compare it with a clearly identified reference. A reading above a historical mean or median indicates a richer valuation relative to that particular reference and series. It does not mean the market is certain to fall or must return to that level. Historical averages describe the period and methodology behind them; they are not universal targets. If a chart supplies both a mean and a median, keep track of which statistic you are using rather than treating them as interchangeable.
- Check that the comparison is like for like. Confirm index coverage, inflation adjustment, earnings definition, and dividend treatment before comparing two CAPE values. A difference in construction can make apparently similar figures meaningfully different. In particular, distinguish conventional price-only CAPE from total-return CAPE, and check whether the displayed observation uses an alternative adjustment.
- Put the ratio alongside other evidence. Look at conventional trailing or forward P/E, earnings yield, real interest rates, and the time horizon and risk capacity relevant to your decision. Valuations reflect expectations about future payoffs as well as interest rates and risk premiums; those forces cannot be reduced to one ratio. The Federal Reserve’s valuation discussions use interest-rate and risk-premium context rather than treating a single valuation measure as a complete verdict.
- Do not turn it into an all-or-nothing timing rule. CAPE can inform long-term valuation assumptions and uncertainty about expected returns. It cannot establish a precise crash date, guarantee a future return, or determine an individual investor’s allocation by itself. If you are already following an investment plan, a high or low reading alone is not a reason supplied by this ratio to abandon it.
What does a high or low CAPE mean?
A high reading
A high CAPE means the current index price is high relative to the average of its past ten years of inflation-adjusted earnings. It is a signal about the price investors are paying against that earnings history—not proof that stocks are about to crash. Prices can remain elevated while expectations, interest rates, earnings, and perceived risk change.
The Federal Reserve’s discussion of asset valuations emphasizes that observed prices can reflect expected future payoffs, interest rates, and risk premiums. Risk premiums are not directly observable, making it difficult to isolate why a valuation is high or to infer a specific near-term outcome. See the Federal Reserve’s May 2021 Financial Stability Report discussion of asset valuations.
That distinction answers a common question: “Is the S&P 500 overvalued based on CAPE?” You can say that a reading is elevated relative to a named historical reference—for example, the mean shown by a particular provider—if the comparison uses the same series. “Overvalued” can imply that there is one objectively correct price and that the market must move toward it. CAPE by itself does not establish either conclusion. It shows a relationship between today’s price and a historical earnings measure; it does not calculate a guaranteed fair-value level.
A low reading
A low CAPE means the index price is lower relative to the ten-year inflation-adjusted earnings average than it is at a higher reading. It does not guarantee a rebound: the measure does not specify when prices may change or whether earnings will hold up. Treat low and high values as historical valuation context, not as buy or sell instructions.
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A low figure should also be checked for what is happening in its denominator. Because CAPE averages ten years of real earnings, it may reflect more than the latest earnings report. The ratio is deliberately less dependent on a single year, but the inputs still come from historical earnings and CPI data spanning different periods and market conditions.
A dated example: Multpl’s October 8, 2026 snapshot
Multpl displayed a Shiller P/E of 41.62 at the October 8, 2026 close. Its chart also displayed a historical mean of 17.42, a median of 16.13, and a maximum of 44.19 in December 1999. These are Multpl’s displayed figures, not a fresh independent calculation. The current reading is a dated snapshot, and the historical statistics are provider-displayed summaries; their meaning depends on the series and history used. The Multpl Shiller P/E chart is the cited source for those figures.
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The comparison shows how to read a dated observation: 41.62 was well above the mean and median displayed on that same chart, while below the chart’s stated December 1999 maximum. That comparison does not establish a fair value, predict a crash, or tell an investor to buy, sell, or wait. These values are a snapshot for the date stated, not a timeless current reading. If you consult the chart later, check its displayed observation date rather than repeating 41.62 as though it were still current.
The displayed mean and median are also not interchangeable with a forecast. They summarize a particular provider’s historical series. Their usefulness depends on the selected history and definitions, and the cited sources do not establish a return forecast from this snapshot. The example is useful for practicing comparison, not for inferring how quickly or whether a ratio might move toward its past average.
Compare CAPE with other valuation measures
Different valuation ratios answer different questions. Before comparing them, check the following construction and context details:
| What to check | Questions to ask | Why it matters |
|---|---|---|
| Earnings window | Does the denominator use trailing one-year earnings, forward estimates, or a ten-year average? | A single year may be unusually strong or weak; forward estimates depend on forecasts. |
| Inflation treatment | Are earnings nominal or adjusted for inflation? | CAPE’s historical earnings denominator is inflation-adjusted. |
| Payout treatment | Is the measure price-only or based on total return, and how does it treat dividends and buybacks? | Changes in payout policy can affect earnings-per-share comparisons and the relationship between price and earnings. |
| Interest-rate context | How do real Treasury yields and equity earnings yield compare? | Interest rates and risk premiums affect how investors value future payoffs. |
| Data provenance and date | Which dataset, provider, index coverage, and update date does the figure use? | Different sources and variants may not be directly comparable. |
A conventional trailing P/E uses a shorter earnings window, while a forward P/E uses estimated future earnings. CAPE instead uses ten years of inflation-adjusted historical earnings. Those denominators answer different questions; one measure is not automatically a correction for the others. A comparison is most useful when you name each measure and explain what its earnings base represents.
Earnings yield is the reciprocal framing of a price-to-earnings measure: it expresses earnings relative to price rather than price relative to earnings. The Federal Reserve’s October 2023 Financial Stability Report discussion of asset valuations considers forward P/E and earnings yield relative to the real 10-year Treasury yield. That comparison adds interest-rate context; it does not turn any one measure into a complete valuation verdict. The 2021 report also explains why observed prices can reflect expected cash flows, rates, and risk premiums, with the risk premium itself not directly observable.
For a practical comparison, write down the name of each measure, its date, and what earnings or yield it uses. Then ask whether the measures point to different conclusions because of their windows or assumptions. Do not compare a conventional CAPE number with a total-return CAPE number, or a historical-earnings measure with a forward estimate, without making those differences explicit.
Why CAPE’s construction matters
Historical earnings and inflation data
The earnings denominator is assembled from historical data covering changing market and accounting environments. Shiller’s Yale documentation describes using multiple sources, including S&P four-quarter earnings data for later periods and earlier historical series, with CPI adjustments. A long history allows a broad comparison, but it does not make every observation perfectly comparable across eras.
This is one reason to identify the data source rather than relying on a bare number copied from a chart or article. Historical earnings series and presentations may be revised, while providers may also differ in coverage or construction. The price component changes more frequently than a ten-year earnings average, so a reading’s date matters even when its label remains the same.
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Dividends, buybacks, and total-return CAPE
Corporate payout policy can affect how earnings per share compare over time. Shiller notes that share repurchases have become a dominant way of distributing cash relative to dividends, and that changes in payout policy may affect CAPE through both earnings-per-share growth and the average real earnings used in the calculation.
Shiller’s data page provides a total-return CAPE alternative. It reinvests dividends into the price index and adjusts earnings per share in response to concerns about changing payout policy. This is a distinct construction, so do not compare its value with a conventional CAPE reading as though the definitions were identical. The Yale data documentation describes the alternative and the historical series.
The existence of the alternative is a reminder that ratio construction involves choices. It does not mean that one version is universally correct for every comparison. First determine which question you are asking and which series answers it; then compare values produced on a consistent basis. If a chart does not make its payout treatment clear, treat that as a reason to verify the methodology before drawing a conclusion.
What CAPE cannot tell you
- It cannot time a market turn. A long-term valuation comparison does not identify a date when prices or earnings will adjust.
- It cannot separate the causes of a valuation. Expected cash flows, interest rates, and risk premiums can all affect prices, and their contributions are difficult to distinguish.
- It cannot make historical averages into targets. A mean or median depends on the chosen period and series definition.
- It cannot determine what is suitable for you. A broad index ratio does not account for your goals, liquidity needs, time horizon, diversification, tax position, or risk tolerance.
- It cannot provide a complete return forecast by itself. The cited sources do not establish a specific point-return prediction suitable for this example. Do not turn a historical relationship or chart statistic into a guaranteed future outcome.
So, does a high CAPE mean stocks will crash? No. It means price is high relative to the defined historical real-earnings average. The ratio alone cannot say whether a decline will occur, when it might occur, or whether earnings and expectations will change instead. A high reading may prompt you to examine assumptions about valuation and future payoffs, but it is not a crash signal with a date attached.
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- Write down the observation. Note the number, provider, date, and whether it is conventional or a variant such as total-return CAPE. Keep the observation date with the value so a later reader does not mistake a snapshot for an up-to-date figure.
- Read the denominator definition. Verify that the measure uses a ten-year average of inflation-adjusted earnings and understand any stated payout or index adjustments. Check whether the source explains CPI treatment and the earnings data behind its series.
- Choose a relevant comparison. Use a historical mean or median only when you can identify the series and period it describes. Treat the comparison as descriptive, not as a price target. Avoid presenting a provider’s displayed statistic as a universal fair-value benchmark.
- Check complementary measures and conditions. Compare with trailing or forward P/E and earnings yield, then consider real interest rates and the assumptions behind expected future payoffs. Confirm that the compared measures are dated and defined consistently enough to be informative.
- Make the decision using your own plan. Use CAPE to question long-run return assumptions or valuation risk, not as a substitute for an allocation plan based on your time horizon, diversification, liquidity, and ability to withstand losses. A broad index ratio cannot incorporate your tax position, cash needs, or personal risk tolerance.
In short, CAPE is most useful as a disciplined question rather than a command: how does the current price compare with a long history of real earnings, and what assumptions might explain that comparison? Answering that question requires checking the series and its date, considering alternative measures and interest-rate context, and keeping the result separate from a short-term market forecast.
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Further reading
Shiller’s Yale data page is a useful primary source for the historical series and its construction notes. Readers who want a broader discussion of the historical stock-market context can also look for Robert J. Shiller’s Irrational Exuberance; verify the edition and availability through a current bookseller. The book is optional background, not a requirement for using CAPE.
Frequently Asked Questions
What is the Shiller P/E ratio?
The Shiller P/E, or CAPE/P/E10, divides the current index price by the average of ten years of inflation-adjusted earnings. This longer window reduces the influence of one unusually high or low earnings year.
How do I calculate the S&P 500 CAPE ratio?
For the familiar series, adjust each of the previous ten years of S&P 500 earnings into current dollars using CPI, average those adjusted earnings, and divide the current index price by that average. Check the provider’s methodology because series variants can use different choices.
Is the S&P 500 overvalued based on CAPE?
CAPE can show that the price is high relative to a named historical real-earnings reference, but the ratio alone does not establish a universal fair value. State the series, date, and comparison being used, and treat the result as valuation context rather than a verdict that prices must fall.
Does a high CAPE mean stocks will crash?
No. A high reading does not identify a crash date or establish that a crash will happen. Prices can reflect expected future payoffs, interest rates, and risk premiums, and CAPE alone cannot separate those influences or predict their timing.
Should I compare CAPE with the historical average?
You can compare it with a mean or median when you identify the provider, series, and history behind that statistic. The comparison is descriptive, not a target or guaranteed fair-value level; different definitions and periods can produce different references.
What is the difference between conventional CAPE and total-return CAPE?
Shiller’s total-return CAPE alternative reinvests dividends into the price index and adjusts earnings per share in response to concerns about changing payout policy. It is a distinct construction, so do not compare its value with conventional CAPE as if the measures were identical.
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The Bottom Line
Use the Shiller CAPE ratio to place the S&P 500’s price in the context of ten years of inflation-adjusted earnings—not to call a market top or set a personal allocation by itself. Check the series, date, and construction; compare like with like; and weigh other valuation measures and interest-rate context. Historical averages are references, not promises about where prices will go.
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