1. What is XIRR?
XIRR stands for Extended Internal Rate of Return. It's the annualised rate of return that accounts for multiple cash flows occurring at different times. It's the metric used by Excel's XIRR function, and by every mutual fund portfolio tracker.
In simple terms: XIRR is the single annual rate at which your irregular investments would have grown if they had grown at a steady rate. It's the "true" annualised return of a SIP.
💡 XIRR formula: Find rate r such that Σ [CashFlowi ÷ (1 + r)ti] = 0, where ti is the time in years of each cash flow.
2. Why SIPs need XIRR, not CAGR
CAGR works only when there's a single initial investment. In a SIP:
- The first instalment is invested for the entire period (say 5 years).
- The middle instalments are invested for varying durations (4.5 years, 4 years, etc.).
- The last instalment is invested for just 1 month.
There's no single "initial amount" or "holding period," so CAGR is meaningless. XIRR solves this by treating each instalment as a separate cash flow and finding the rate that ties them all together.
⚠️ If you calculate CAGR on a SIP by using total invested ÷ number of years, you'll get a wrong number. Always use XIRR.
3. Absolute return vs. XIRR — a worked example
Suppose you invest ₹10,000/month for 3 years (36 instalments). Total invested = ₹3,60,000. Current value = ₹4,50,000.
| Metric | Calculation | Result |
|---|---|---|
| Absolute return | (4,50,000 − 3,60,000) ÷ 3,60,000 | 25% |
| CAGR (incorrect for SIP) | (4.5L ÷ 3.6L)^(1/3) − 1 | 7.72% (wrong) |
| XIRR (correct) | Iterative IRR calculation | ~14.5% |
The CAGR of 7.72% looks terrible — but it's wrong because it assumes all ₹3.6 lakh was invested on day one. In reality, most of it was invested later, so the actual annualised return is much higher (around 14.5%).
4. Step-up SIPs and XIRR
XIRR handles step-up SIPs just as easily. If your SIP increases by 10% every year, XIRR simply accounts for the different cash flow amounts.
| Year | Monthly SIP | Annual investment |
|---|---|---|
| Year 1 | ₹10,000 | ₹1,20,000 |
| Year 2 | ₹11,000 | ₹1,32,000 |
| Year 3 | ₹12,100 | ₹1,45,200 |
A flat SIP of ₹10,000/month for 3 years invests ₹3.6 lakh. The step-up version invests ₹3.97 lakh. XIRR correctly reflects the higher return from the step-up.
5. How to interpret your XIRR
A rough benchmark for equity mutual funds over 5+ years:
| XIRR range | Interpretation |
|---|---|
| Below 8% | Below par — fund may be underperforming |
| 8%–10% | Matching debt funds — not great for equity |
| 10%–14% | Good — typical equity fund performance |
| 14%–18% | Excellent — outperforming benchmark |
| Above 18% | Exceptional — but verify sustainability |
✓ A consistent XIRR of 12%–15% over 10+ years places a fund in the top quartile. Chase consistency, not flashy one-year numbers.
6. XIRR and taxes
The XIRR you see in fund fact sheets is pre-tax. For equity funds held over 1 year, LTCG tax is 10% on gains above ₹1 lakh per year. For debt funds, gains are taxed at your slab rate.
Post-tax XIRR is what you actually keep. On a 14% pre-tax XIRR with a 30% tax slab, the post-tax XIRR might be 11%–12% for debt, or 12.5%–13% for equity (after LTCG).
7. Common mistakes to avoid
- Using CAGR for SIPs. It's mathematically wrong. Always use XIRR.
- Comparing XIRR across very different periods. A 1-year XIRR is noisy. Look at 3-, 5-, and since-inception XIRR.
- Ignoring the benchmark. A 12% XIRR sounds good — until you see the benchmark returned 15%.
- Panicking over short-term XIRR dips. XIRR smooths out over time. A bad year doesn't define a fund.
- Forgetting taxes. Pre-tax XIRR of 14% can become 11% post-tax. Plan accordingly.
- Comparing funds with different cash flow patterns. A step-up SIP and flat SIP have different XIRRs, even in the same fund.
8. A worked example
Suppose you invest ₹15,000/month for 5 years (60 instalments). Total invested = ₹9,00,000. Current value = ₹15,00,000.
- Absolute return: (15,00,000 − 9,00,000) ÷ 9,00,000 = 66.67%
- CAGR (wrong): (15L ÷ 9L)^(1/5) − 1 = 10.76%
- XIRR (correct): ~17.5% (approximate)
- Benchmark XIRR: 12%
- Alpha: +5.5%
The XIRR of 17.5% is dramatically higher than CAGR of 10.76% because the bulk of your money was invested later, so each rupee had a much shorter time to grow — yet grew fast.
9. Final thoughts
XIRR is the only correct metric for measuring SIP returns. If your portfolio tracker shows a "return" for your SIP, it's XIRR — even if they don't say so.
Use this calculator to see your XIRR and how it compares to a benchmark. Then focus on consistency: a fund that delivers 13% XIRR every year beats one that delivers 18% one year and 5% the next.
