Average Return Calculator

This calculator finds your investment's true annualized return — CAGR and geometric mean — from either a start and end value or a list of year-by-year returns, and shows why that number is usually lower than a simple average.

For personal planning only — not financial advice.

Reviewed by CalculatorDrive Finance Editorial Board · Last updated

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Range: 1–100 years

Enter your details, then click Calculate to see your CAGR, average returns, risk metrics, and growth chart.

Average return, in short

There are two ways to average a set of investment returns, and they usually give different answers. Arithmetic mean just adds up the yearly returns and divides by the count. Geometric mean — the basis for CAGR — compounds them the way your money actually compounded, and it's always equal to or lower than the arithmetic mean whenever returns vary from year to year. The more volatile the ride, the bigger that gap gets.

Key takeaways

  • $10,000 growing to $25,000 over 10 years has a CAGR of 9.6% — the single constant annual rate that gets you there.
  • Feed in actual annual returns of 12%, -5%, 18%, 8%, and 15%: the arithmetic mean is 9.6%, but the geometric mean — what your money really did — is 9.29%, for 55.94% total growth.
  • A +50% year followed by a -50% year averages to 0% arithmetically, but $10,000 actually ends up at $7,500 — a real 25% loss. That gap is volatility drag.
  • Standard deviation on the 12/-5/18/8/15 example is about 8.96 percentage points — a way to see the bumpiness behind the average, not just the average itself.

Arithmetic mean vs. geometric mean: two different questions

Arithmetic mean answers "what was the average yearly return?" — a useful number for statistics, but not one that tells you what happened to a dollar invested the whole time. Geometric mean answers "what constant annual rate would have produced this same total growth?" — which is exactly what you want when judging actual investment performance. They're equal only when every period returns exactly the same amount; the moment returns vary, geometric mean falls below arithmetic mean, and it never goes the other way.

How CAGR turns a start and end value into one number

CAGR only needs three things: where you started, where you ended up, and how long it took.

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

= ($25,000 ÷ $10,000)^(1/10) − 1 ≈ 9.6%

That 9.6% doesn't mean any single year actually returned 9.6% — it's the smoothed-out rate that, compounded for 10 straight years, turns $10,000 into exactly $25,000. It's the right number for comparing two investments' overall growth, even if their year-to-year paths looked completely different.

Why volatility drags your real return below the average

Take the starkest case: a portfolio gains 50% one year, then loses 50% the next. Arithmetic mean says the two years average out to 0%. But $10,000 that grows to $15,000 and then falls 50% lands at $7,500 — a real 25% loss, not a wash. Losses and gains aren't symmetric once you're compounding: a 50% loss needs a 100% gain just to get back to even.

The same effect shows up, just more gently, on the calculator's default annual-returns example — 12%, -5%, 18%, 8%, 15%. The arithmetic mean is 9.6%, but the geometric mean is 9.29%, and total growth over the five years is 55.94%, not the 48% you'd get from naively multiplying the arithmetic mean by five years.

Reading the risk metrics

Standard deviation measures how far individual years typically stray from the average — about 8.96 percentage points on the 12/-5/18/8/15 example, meaning a fairly wide spread around that 9.6% mean. Best year, worst year, and the count of positive years fill in the picture further: two portfolios can share the same CAGR while one had a much rockier ride to get there, and standard deviation is what surfaces that difference. The benchmark comparison against typical S&P 500 and bond returns gives a quick sense of whether your number is in a reasonable range for the level of risk involved.

Related calculators

To project future growth at an assumed rate rather than measure past performance, see the compound interest calculator or the investment calculator. For cash flows that aren't just a single start and end value — like contributions added over time — the IRR calculator handles the more general case.

Frequently Asked Questions

What is the difference between arithmetic mean and geometric mean return?

Arithmetic mean adds up each year's return and divides by the number of years. Geometric mean compounds them instead, which is what actually happened to your money. On returns of 12%, -5%, 18%, 8%, and 15%, both average 9.6% arithmetically, but the geometric mean — the true annualized figure — comes out to 9.29%.

Why can the simple average overstate performance?

A 50% gain followed by a 50% loss does not break even. The simple average is 0%, but $10,000 becomes $15,000 then drops to $7,500 — a real 25% loss. Volatility drag means the more returns swing up and down, the further the simple average strays from what actually happened.

What is CAGR?

Compound Annual Growth Rate is the single constant annual rate that would carry a starting value to an ending value over a given span. $10,000 growing to $25,000 over 10 years has a CAGR of 9.6% — the smoothed-out annual rate, even though no single year likely grew by exactly that amount.

What do the risk metrics tell me?

Standard deviation measures how much returns swing year to year — on the 12%, -5%, 18%, 8%, 15% example, that is about 8.96 percentage points. Best year, worst year, and the count of positive years give a quick sense of how bumpy the ride actually was behind the average.

How should I evaluate investment performance over time?

Lean on the geometric mean or CAGR for actual growth, not the simple average. Compare it against a relevant benchmark, and weigh volatility alongside the return — two investments with the same CAGR can feel very different to hold if one swings much harder than the other. Past returns never guarantee future results.

How do I use this average return calculator?

Choose Start/End Values to get CAGR from an initial investment, final value, and number of years, or choose Annual Returns to enter each year's percentage return individually. Click Calculate Returns to see CAGR, arithmetic and geometric mean, and — for annual returns — risk metrics and a benchmark comparison.

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