CAGR vs IRR (and XIRR): What's the Difference?

CAGR (compound annual growth rate) measures how fast a single lump sum grew at one smooth annual rate between a start and an end value, while IRR (internal rate of return) — and its spreadsheet form XIRR — measures the annual return when money flows in and out at different times, so IRR is the right lens the moment you add to or withdraw from an investment.

Both are annualized return figures, and for the simplest case — one amount invested, left alone, and measured later — they give the same answer. The difference shows up as soon as there is more than one cash flow. CAGR only looks at the first and last values and ignores everything in between; IRR takes every deposit and withdrawal, and its exact date, into account.

This guide explains both measures side by side, works through a numeric example where they disagree, and shows when each one fits. You can compute a simple return with the ROI Calculator and view the annualized figure for a single lump sum with the Total Return Calculator; for the multiple-cash-flow case, this article explains what IRR and XIRR add.

Who Is This Guide For?

This article is for investors who have seen both figures quoted — perhaps a fund's CAGR and a spreadsheet's XIRR — and weren't sure why they differ, or who make regular contributions and want a return number that reflects that. It is slightly more advanced than a basic returns explainer, but no finance background is needed. It suits anyone who wants to:

• understand what CAGR and IRR each actually measure,
• see why they agree for a single lump sum but diverge once you add or withdraw money,
• learn what XIRR is and why spreadsheets use it for irregular cash flows,
• and know which return figure fits a portfolio you keep contributing to.

It is educational, not advice, and every figure below holds "under these assumptions."

CAGR vs IRR at a Glance

Both express a return as a single annual percentage, but they are built for different situations: one for a single untouched sum, the other for a stream of cash flows.

The key line is what it uses. CAGR looks only at the endpoints; IRR looks at everything in between. That single difference explains every disagreement between the two.

What CAGR Is

CAGR — the compound annual growth rate — is the single, steady annual rate that would turn a starting value into an ending value over a given number of years, assuming the money compounded smoothly and nothing was added or taken out along the way.

Its formula is:

CAGR = (Ending value ÷ Starting value) ^ (1 ÷ number of years) − 1

CAGR is anchored to just two numbers: where you started and where you ended. That makes it clean and easy to compare across investments held for different lengths of time, because everything is expressed on the same per-year basis. It is the natural measure for a single lump sum — you put money in once, leave it, and later ask how fast it grew.

CAGR's limitation is the flip side of its simplicity: because it only sees the endpoints, it cannot account for money moving in or out in between. If you added to the investment halfway through, CAGR would treat that new money as if it had been there the whole time, which overstates or understates the true rate depending on the timing.

What IRR and XIRR Are

IRR — the internal rate of return — is the annual rate that makes the value of all the money you put in equal the value of all the money you took out (including the final balance), once each cash flow is discounted back to the start. Put more plainly, it is the single rate that "explains" a whole series of deposits and withdrawals, not just a start and an end.

Because it depends on every cash flow, IRR cannot be found with one direct formula. Instead it is solved by iteration — a spreadsheet or calculator tries rates until it finds the one at which the discounted inflows and outflows balance out to zero. Conceptually:

IRR is the rate r for which the sum of every cash flow ÷ (1 + r) ^ (its time) equals zero.

IRR assumes the cash flows happen at regular, equal intervals (for example, once a year). Real investing is rarely that tidy — you might invest on odd dates, skip a month, or withdraw mid-year. That is what XIRR handles: it is the same idea as IRR, but it takes the exact date of each cash flow, so irregular, real-world timing is measured correctly. In spreadsheets, IRR is the equal-period function and XIRR is the dated one; for most personal portfolios with uneven contributions, XIRR is the one that applies. See the XIRR glossary entry for a fuller definition.

The strength of IRR and XIRR is that they reflect what actually happened to your money, timing and all. Their limitation is that they are more involved to compute, they need a full record of your cash flows and dates, and in unusual cases (cash flows that switch sign more than once) a series can technically have more than one IRR.

A Worked Example

Case 1 — a single lump sum (CAGR and IRR agree).

You invest $10,000 once and it grows to $16,000 over 5 years, with no money added or withdrawn.

CAGR = ($16,000 ÷ $10,000) ^ (1 ÷ 5) − 1 = (1.6) ^ 0.2 − 1 ≈ 9.86% per year

Here IRR would return the same figure — about 9.86% — because there is only one deposit and one final value. With a single cash flow, IRR reduces to CAGR.

Case 2 — regular contributions (they now disagree).

Now suppose you invest $10,000 at the start of each year for 5 years — $50,000 in total — and end with a balance of $65,000.

A naive CAGR is tempting: total in $50,000, total out $65,000, so ($65,000 ÷ $50,000) ^ (1 ÷ 5) − 1 ≈ 5.39% per year. But that treats all $50,000 as though it was invested for the full five years, which it was not — the final $10,000 was only invested for one year. It flatters the early money and penalizes the late money, so the number is misleading.

IRR (or XIRR, if the dates are irregular) fixes this by weighting each contribution for the actual time it was invested. Solving for the rate that balances five annual $10,000 deposits against a $65,000 ending value gives an IRR of roughly 9% per year under these assumptions — noticeably higher than the naive 5.39%, because most of the money was invested for far less than the full five years.

The two numbers describe the same account but answer different questions. The naive CAGR pretends the money arrived all at once; IRR respects when each dollar actually went in. This is exactly the situation IRR and XIRR are built for, and where CAGR alone can mislead.

Which to Use When

Neither measure is "more accurate" in general — they are built for different situations, so the right one depends on how the money moved. The guide below is framed around the cash-flow pattern, not around which figure is superior.

CAGR tends to be the useful lens when:

• a single amount was invested once and left alone,
• you only have the start value, the end value, and the number of years,
• you want a clean, comparable annual rate across investments held for different periods,
• or you are describing the growth of one holding rather than a portfolio you keep funding.

IRR (or XIRR) tends to be the useful lens when:

• money went in or came out at more than one point in time,
• you make regular or irregular contributions, or take withdrawals,
• the timing of those cash flows matters to the return,
• or you want a single annual rate that reflects your actual deposit and withdrawal history — for uneven dates, XIRR is the version that fits.

A practical rule of thumb: if there is exactly one cash flow in and one out, CAGR and IRR are the same and CAGR is simpler; the moment there is a second cash flow, IRR or XIRR is the measure that accounts for it. When you want to compute a straightforward return for your own numbers, use the ROI Calculator for the total percentage gain and the Total Return Calculator for the annualized (CAGR) view of a single lump sum; for a full multi-cash-flow history, a spreadsheet's XIRR function is the tool that applies.

Key Takeaways

• CAGR measures how fast a single lump sum grew, using only the start and end values.
• IRR measures the annual return when there are multiple cash flows, weighting each for when it happened; XIRR is the version that uses exact dates for irregular timing.
• For one deposit and one final value, CAGR and IRR give the same answer.
• Once you add or withdraw money, a naive CAGR can mislead because it ignores timing — IRR or XIRR is the measure that accounts for it.
• Use CAGR for a single untouched investment; use IRR or XIRR for a portfolio you keep contributing to or drawing from.

Continue Learning

To build on these ideas, continue with:

• ROI vs CAGR
• CAGR vs Average Annual Return
• What Is Compound Interest?

Together they explain how total return and annual growth differ, why the average of yearly returns overstates real compounded growth, and how compounding builds a balance over time.