CAGR vs Average Annual Return: Why the Two Numbers Disagree

An investment that goes from $10,000 to $25,000 over five years grew 150% in total. It did not grow at a steady 30% a year, even though 150% divided by five years equals exactly that. The actual year-by-year growth rate — the one that correctly accounts for compounding, where each year's growth builds on the year before rather than on the original amount — is about 20.1%. The gap between those two numbers, 30% and 20.1%, is the entire reason CAGR exists as a separate figure from simple average annual return.

The Formula

CAGR = (Ending Value ÷ Starting Value)^1/Years − 1

The exponent — 1 divided by the number of years — is what makes this a compound rate rather than a simple one. It finds the single constant annual growth rate that, applied every year and compounded on the growing balance, would take the starting value to the ending value over the given period.

Why Simple Average Overstates Growth

Dividing total percentage growth by the number of years — what CAGR calculators often show alongside CAGR itself, labeled as simple annual return — ignores that growth compounds on an increasingly larger base each year. A 150% total gain over five years divided evenly gives 30% a year. But 30% compounded annually for five years produces a total gain of roughly 271%, not 150% — the simple average, applied as if it were a compound rate, overstates where the investment actually ended up. CAGR corrects for this by finding the rate that, compounded, lands exactly on the real ending value.

A Worked Example

$10,000 growing to $25,000 over 5 years: CAGR = (25,000 ÷ 10,000)^1/5 − 1 = 2.5^0.2 − 1 ≈ 1.2011 − 1 = 0.2011, or about 20.11% per year.

Checking the math in reverse confirms it: $10,000 compounded at 20.11% annually for five years grows to $10,000 × 1.2011⁵ ≈ $25,000 — the starting value, grown at a single constant rate, lands exactly on the real ending value. That reversibility is the actual definition of CAGR: not an average of anything, but the one constant rate that reconstructs the real outcome.

Where CAGR Hides More Than It Shows

CAGR describes the overall path from start to end, but it says nothing about what happened in between. Two investments with an identical CAGR can have completely different return profiles — one growing smoothly and predictably every year, another swinging between large gains and large losses that happen to average out to the same compound rate over the full period. An investment that dropped 40% in year three and recovered sharply afterward can post the same five-year CAGR as one that never had a losing year, and CAGR alone cannot tell the two apart.

This matters most for anyone evaluating risk, not just return. A high CAGR achieved through a volatile path carries real risk a low-volatility path to the same CAGR does not — standard deviation of annual returns, or simply looking at the year-by-year numbers rather than the single compound figure, is what actually surfaces that difference.

What CAGR Does Not Account For

CAGR as calculated from a starting and ending value assumes no additional contributions or withdrawals during the period — it describes the growth of a single lump sum left untouched. An investment account with regular contributions needs a different calculation (commonly an internal rate of return or a money-weighted return) to account for new money entering at different points, since CAGR applied naively to a contribution-growing account would misattribute new deposits as investment growth.

CAGR also does not adjust for inflation. A 20% nominal CAGR during a period of 5% annual inflation represents meaningfully less real purchasing-power growth than the same nominal CAGR during a period of 1% inflation — the figure itself is a nominal rate unless explicitly adjusted.

Frequently Asked Questions

Is CAGR the same as average annual return?

No — average annual return (also called simple annual return) divides total percentage gain evenly across the years, while CAGR finds the compound rate that actually reconstructs the ending value from the starting value. CAGR is always equal to or lower than the simple average for any investment with positive overall growth, because compounding on a growing base needs a lower constant rate to reach the same endpoint that simple averaging implies.

Can CAGR be negative?

Yes — if the ending value is lower than the starting value, CAGR comes out negative, representing the compound rate of decline over the period rather than growth.

Does CAGR work for periods under one year?

The formula works mathematically for any positive time period, including fractional years, but CAGR is conventionally used for multi-year comparisons specifically because it is meant to smooth out short-term volatility into a single long-run rate — applying it to a period of a few months defeats that purpose and a simple percentage change is more informative at that timescale.

Why do two investments with the same CAGR sometimes feel like very different outcomes?

Because CAGR only describes the relationship between the starting and ending value, not the path between them. A smooth, steady climb and a volatile path with a severe drawdown in the middle can both compound to the same CAGR over the full period, while representing very different risk experiences along the way.

Should CAGR be adjusted for inflation when comparing investments over different eras?

Yes, for a fair comparison — a nominal CAGR earned during a high-inflation period represents less real growth than the same nominal CAGR earned during a low-inflation period. Subtracting the average inflation rate over the same span (or using the Fisher equation for a more precise adjustment) gives a real CAGR comparable across different time periods.

Calculate CAGR, total return, and a year-by-year growth schedule for your own numbers with the CAGR Calculator.