CAGR vs XIRR: Which One Actually Measures Your Returns?

You have been running a ₹10,000 monthly SIP for ten years. You have put in ₹12 lakh. It is worth ₹23 lakh. What return did you get?

Divide 23 by 12, take the tenth root, subtract one, and you get 6.7%. That feels low for ten years of equity, and it is — the calculation is wrong.

The right answer is about 12.5%, and the reason for the gap is the single most useful thing to understand about measuring investment returns.

What each measure is for

CAGR — compound annual growth rate — answers: if this had grown at a steady annual rate, what rate would it be? It needs exactly two numbers and two dates. One amount in, one amount out.

XIRR — extended internal rate of return — answers the same question when money went in or out at many different times, weighting every cash flow by how long it was actually invested.

For a lump sum they give an identical answer. For a SIP they diverge, sometimes dramatically.

Why the naive number is so wrong

The ₹12 lakh was never invested for ten years.

Your first ₹10,000 has been invested for the full 120 months. Last month's ₹10,000 has been invested for one. On average, each rupee has been invested for a little over five years, not ten.

Treating the whole ₹12 lakh as though it had been sitting there since day one asks the money to have worked twice as long as it did — so the rate required to reach ₹23 lakh looks half as impressive as it really was.

XIRR corrects this by discounting each instalment from its own date. Every rupee gets credit for exactly the time it was invested.

The three numbers people confuse

Take the same SIP:

Measure	Value	What it says
Absolute return	91.7%	Total growth, no reference to time. Useless for comparison.
CAGR on total invested	6.7%	Wrong for a SIP — assumes day-one lump sum.
XIRR	12.5%	The actual annualised return.

Absolute return is the one fund marketing materials like, because it is the biggest number. It tells you nothing on its own — 91.7% over ten years is ordinary; over three years it would be excellent.

When to use which

Use CAGR when there is exactly one investment and one value. Bought ₹1 lakh of a fund in 2016, worth ₹2.6 lakh now — CAGR is correct and XIRR would return the identical figure.

Use XIRR the moment there is more than one cash flow in either direction: a SIP, an SWP, lump-sum top-ups, partial redemptions, a switch between funds. Which is to say, almost every real portfolio.

Do not compare your XIRR to a fund's advertised CAGR

This trips people up constantly. A fund's published "5-year return" is a point-to-point CAGR for a lump sum invested at the start of that window. Your XIRR reflects your own contribution timing.

If you started your SIP shortly before a drawdown, your XIRR will trail the fund's published CAGR even though you did nothing wrong. If you started before a rally, you will beat it. Neither number is lying; they measure different things.

To judge the fund, compare its returns against its benchmark and its category. To judge your outcome, use XIRR.

Calculating it

For a level monthly SIP, the XIRR calculator needs three inputs — your monthly amount, the number of years, and the current value — and shows the naive CAGR alongside so you can see the gap on your own numbers.

For an irregular history, use the XIRR() function in Excel or Google Sheets. Put every transaction date in one column and the amount in the next, investments as negative numbers and the current value as a positive one, then call XIRR(values, dates). Your consolidated account statement from CAMS or KFintech lists every dated transaction across all your funds, which is exactly what the function needs.

Two caveats

XIRR assumes interim cash flows are reinvested at the same rate — a standard IRR assumption that rarely holds exactly, and one reason XIRR slightly flatters portfolios with large mid-period withdrawals.

It can also become unstable when cash flows change sign more than once, where more than one mathematically valid answer exists. For an ordinary accumulating SIP neither issue arises.

The short version

• Absolute return ignores time. Never compare with it.
• CAGR is right for one-in, one-out. It is wrong for a SIP and will understate you badly.
• XIRR is right whenever money moved more than once.
• A negative XIRR in the first year or two of an equity SIP is normal. Over seven years it is a signal.