Your SIP statement says one thing. The number you worked out on a calculator says another. And neither matches what your colleague swears his fund delivered.
Most of that confusion traces back to one habit: running SIP investments through a CAGR calculator and trusting whatever percentage comes out. It feels logical.
But a SIP is not one investment. It is dozens of them, each starting on a different date, and CAGR has no way of seeing that.
CAGR Assumes You Invested Once And Never Touched It
CAGR answers a narrow question.
If a single amount grew from one value to another over a fixed period, what steady yearly rate would explain that growth? The formula divides the ending value by the starting value, raises the result to the power of one over the number of years, and subtracts one. Clean, simple, and genuinely useful.
But look at what that formula needs. One starting value, one ending value, one start date. That is the entire input set.
For a lump sum parked in a fund, a CAGR calculator does exactly what you want. You invested once, on one day. No complications.
A SIP breaks every one of those assumptions.
The Point Where SIP Return Calculations Stop Making Sense
Picture a three-year SIP. Your first installment has been invested for the full three years. Your latest went in barely a month ago. Somewhere in between sit thirty-odd others, each with its own holding period.
Now feed the total invested amount and the current value into the formula and tell it the period is three years. What have you just done? You have told it that every rupee sat in the market for three years. Most of it did not (your latest instalments have barely started working).
When markets have been kind, the figure understates how hard your money worked, because growth gets spread across time your money never spent invested. When markets have been unkind, it makes losses look milder than they were. Either way, the number is not describing your experience.
Here’s the thing. The CAGR calculator is not broken. You have simply asked it a question it was never designed to answer.
XIRR: Built for Money That Arrives in Instalments
XIRR, short for Extended Internal Rate of Return, starts from a different premise. Instead of one start and one end, it accepts a full list of cash flows with their exact dates. Every SIP installment goes in as an outflow on the day it was debited. Any redemption goes in as an inflow, and the current value of your holdings sits at the end as the final inflow.
From there, XIRR works backwards to find the single annualized rate that makes all those dated cash flows balance out. Each installment gets credit only for the time it was actually invested.
That one change fixes the distortion.
It also copes with the untidy things real investors deal with, like a skipped installment, a step-up in the SIP amount, or a partial withdrawal halfway through. CAGR cannot absorb any of that.
So When Does a CAGR Calculator Still Earn Its Place?
More often than its critics admit. When you check how a fund’s NAV has moved over a fixed three- or five-year window, you are looking at a point-to-point figure, and CAGR is exactly the right lens for that.
| Situation | Better measure | Why |
| Single lump sum investment | CAGR | One amount, one date, one holding period |
| Monthly SIP | XIRR | Every installment has its own holding period. |
| SIP with step-ups or skipped installments | XIRR | Irregular amounts and dates need individual treatment |
| A fund’s NAV growth over a fixed period | CAGR | One start value, one end value |
| Portfolio with additions and withdrawals | XIRR | Money moves in and out at different times. |
Notice the pattern. One cash flow, CAGR. Many cash flows, XIRR.
How To Calculate Your Actual Returns Without Trusting The App
You do not need specialist software. Any spreadsheet with an XIRR function will do the job. List every installment date in one column and the amount as a negative value beside it, then add today’s date with your current portfolio value as a positive figure. Apply the function across both columns and you have your answer.
For lump sum checks, a reliable cagr calculator gets you there in seconds with no spreadsheet at all. I’d keep both and match the tool to the investment.
Conclusion
A SIP is a habit, not a single bet. Treating it like one, which is what a CAGR calculator does when you feed it SIP data, hands you a number that looks precise and means very little.
XIRR respects the timing of every rupee you put to work. That makes it the figure worth trusting for a SIP.
Before you take any return figure at face value, ask what it assumes about when your money went in. The answer usually tells you whether to believe it.