What Is CAGR? Compound Annual Growth Rate, Explained

CAGR, or compound annual growth rate, is the single steady annual rate that would take a starting value to an ending value over a given number of years. It is the most common way to express a long-run return in one number, and its usefulness and its blind spot come from the same feature: it completely smooths away everything that happened in between.

If a value doubles over five years, CAGR tells you the constant yearly rate that would have produced that doubling. It does not tell you whether the journey was a calm climb or a violent round trip that happened to end in the right place.

What it measures

The definition in words is simple. Take the ending value and divide it by the starting value. That gives you the total growth multiple over the whole period. Then ask what constant yearly rate, compounded once a year, would produce that same multiple over that number of years. That rate is the CAGR.

In arithmetic terms you raise the growth multiple to the power of one divided by the number of years, and subtract one to turn it back into a percentage.

A hypothetical example makes it concrete. Suppose a portfolio is worth 100 at the start and 200 at the end of five years. The growth multiple is 2. The constant annual rate that compounds to a doubling over five years is roughly 14.9 percent. So the CAGR is about 14.9 percent, even if the actual yearly returns were wildly uneven.

Notice what the calculation uses: two values and a length of time. Nothing else. It does not look at the years in between, it does not look at how much the value swung, and it does not look at any money added or taken out along the way.

Three points follow from that.

CAGR is a geometric average, not an arithmetic one. A simple average of yearly returns adds them up and divides. CAGR chains them together the way money actually compounds. Suppose a hypothetical investment falls 50 percent in year one and rises 100 percent in year two. The simple average is 25 percent a year, which sounds excellent. But 100 falls to 50, then doubles back to 100. The value has not moved. The CAGR is zero. That gap between the two averages is not a rounding quirk. It is the arithmetic of compounding, and it grows wider the more the returns bounce around.

CAGR assumes no cashflows. It compares a single starting value to a single ending value. If money was added or withdrawn during the period, CAGR is measuring the wrong thing, because part of the change in value came from contributions rather than growth. That is the job of a cashflow-weighted measure. The distinction is covered in CAGR vs XIRR vs absolute returns.

CAGR is entirely determined by two dates. Move the start date or the end date, and the number changes, sometimes dramatically. This is the single most important thing to understand about it.

How to read it

Start by asking what the two dates are. A CAGR is a statement about one specific window, and the choice of window does most of the work. A period that begins near a market trough and ends near a peak will produce a flattering number. The same strategy measured over a window shifted by a few months can look ordinary. Whenever you see an impressive long-run CAGR quoted, the first honest question is not “how was it calculated” but “why those dates”.

Next, ask how long the period is. Short windows annualised into a CAGR are the least reliable form of the number, because a small amount of noise gets projected onto a yearly rate. Longer windows are more stable, but they also hide more, because more years of variation get compressed into one figure.

Then compare like with like. A CAGR only means something next to a reference point measured over the identical window: a benchmark, a peer, or the same portfolio under a different rule set. Comparing a five-year CAGR to someone else’s three-year CAGR is not a comparison at all.

Finally, read CAGR alongside a measure of the path. Two portfolios can share the same CAGR and be completely different experiences to hold. The pairing that professionals reach for is a return measure plus a risk measure: CAGR next to maximum drawdown, or CAGR next to volatility. The return says where you ended up. The risk measure says what you had to live through to get there.

CAGR is a summary of a destination. It says nothing about the road. Any serious use of it pairs it with something that describes the road.

What it does not tell you

CAGR is a single number doing an enormous amount of compression, so the list of things it cannot see is long and worth knowing.

It does not tell you the path. Every intermediate year is erased. A portfolio that ground steadily upward and one that halved before recovering can report the identical CAGR. Investors experience the path, not the summary.

It does not tell you the risk. There is no volatility, no drawdown, no measure of how far the value fell below its previous high, and no sense of how long recoveries took. CAGR is a return measure only. Risk-adjusted measures such as the Sharpe ratio exist precisely because return alone is incomplete.

It does not tell you about consistency. Because it depends only on the endpoints, CAGR cannot distinguish a result driven by one exceptional year from one built out of many ordinary years. This is the specific gap that rolling returns are designed to fill, by measuring every possible window rather than one.

It does not handle contributions or withdrawals. For a real investor account with money going in and out, CAGR measured from opening balance to closing balance mixes up growth with deposits. It is the wrong tool for that job.

It is not a forecast. A past CAGR describes what happened over one window under one set of conditions. Nothing in the calculation carries information about the future, and treating a historical CAGR as an expected rate is one of the more common errors in investment writing.

It says nothing about costs or taxes unless you build them in. A CAGR computed on gross values ignores brokerage, other transaction costs, fund expenses, and taxes. Whether a number is gross or net changes what it means, and the difference compounds over long periods just as returns do. If the number came from a historical simulation, it also inherits every assumption that simulation made, which is why common backtesting mistakes matter to anyone reading a headline growth rate.

It can be distorted by the data underneath it. If the historical values used to compute it were revised after the fact, or if the price series was not adjusted for splits and bonuses, the CAGR is measuring a history that was never actually available at the time. This is the practical reason point-in-time data matters.

Used with those limits in mind, CAGR remains genuinely useful. It is the cleanest way to put long-horizon growth on a comparable annual scale, and it is the natural starting point for almost every performance discussion. It is simply a starting point, not a conclusion.

Related reading

• Portfolio metrics explained: the hub that maps how return, risk and trade statistics fit together.
• CAGR vs XIRR vs absolute returns: which return measure is correct when cashflows enter and leave.
• Rolling returns explained: why measuring every window beats measuring one.
• What is maximum drawdown: the risk figure that belongs next to any growth rate.
• Buy and hold vs strategy returns: the baseline any reported CAGR should be compared against.

This article is educational. Altys Labs is not a registered research analyst or investment adviser, and nothing here is investment advice or a recommendation to buy, sell, or hold any security.