What is XIRR? How SIP returns are really measured

XIRR (Extended Internal Rate of Return) is the single annualised return percentage for a series of investments and withdrawals made on different dates. For a SIP — where you invest a bit every month — it's the only fair way to express "what return did I actually earn?" Every instalment has been invested for a different length of time, and XIRR is the one number that accounts for all of them at once.

Why not just use absolute return?

If you SIP ₹5,000/month for 5 years (₹3,00,000 invested) and it grows to ₹4,20,000, the absolute return is 40%. But that 40% is misleading — your first instalment was invested for 5 full years, while your last one was invested for just a month. Dividing one number by another ignores time completely. XIRR accounts for exactly how long each rupee was invested, giving a true annual rate (here, roughly 12% p.a.).

This is also why two investors in the same fund can honestly report different returns: one who started their SIP before a rally will show a higher XIRR than one who started at the top, even though the fund's own chart is identical for both.

How it's calculated

XIRR finds the single annual rate that makes the present value of all your cash flows equal to zero. Each instalment is a dated cash outflow; the final value is a dated inflow. It's the same logic Excel's XIRR() uses, and the same maths banks use to price loans — just pointed at your SIP instead.

A worked example

Say you invested ₹10,000 on 1 January, another ₹10,000 on 1 July, and the holding is worth ₹22,000 on 31 December. Absolute return says 10%. But the first ₹10,000 worked for 12 months and the second for only 6 — XIRR resolves this to roughly 13% p.a., the rate that, applied to each dated cash flow, lands exactly on ₹22,000. The more irregular your investing, the further absolute return drifts from the truth.

XIRR vs CAGR — when to use which

• Use XIRR for SIPs, STPs, top-ups, partial redemptions — any investing with multiple dates.
• Use CAGR for a single lumpsum held over one period — for a one-shot investment, CAGR and XIRR agree.
• A higher XIRR isn't automatically "better" — check the fund's risk and consistency too.

Common mistakes with XIRR

• Comparing a 6-month XIRR with annual returns. XIRR annualises, so short-period numbers get exaggerated in both directions — a good quarter can print a meaningless 60% XIRR.
• Ignoring cash flows you forgot. Dividends taken out, a partial withdrawal, a skipped instalment — every dated flow changes the answer.
• Judging a fund by your personal XIRR. Your entry timing is part of your number. To judge the fund itself, look at its NAV history and rolling returns in the screener.

→ See your numbers with the SIP & XIRR calculator, or backtest a real fund's SIP XIRR in the Backtest tab.