Lead Developer & Quantitative Analyst
Executive Summary
When assessing personal portfolio performance, investors routinely confuse CAGR (Compounded Annual Growth Rate) and XIRR (Extended Internal Rate of Return). Using CAGR for a monthly Systematic Investment Plan (SIP) or an irregular lump-sum portfolio produces wildly misleading return numbers. In simple terms: CAGR measures point-to-point growth of a single cash deposit, while XIRR measures the true annualised yield across multiple deposits and withdrawals at distinct calendar dates.
1. What is CAGR? The Point-to-Point Benchmark
Compounded Annual Growth Rate (CAGR) is the constant annual rate of return that would be required for an initial investment to grow from its beginning balance to its ending balance over a specified number of years.
Where Years is the total elapsed time in fractional or whole calendar years.
When CAGR is Ideal:
- Evaluating a one-time lump sum mutual fund or stock investment held for 5 years.
- Comparing the multi-year performance of mutual fund category benchmarks (e.g. Nifty 50 10-year CAGR).
- Measuring corporate revenue or earnings per share (EPS) growth over time.
2. Why CAGR Fails Completely for SIPs
Consider an investor who starts an SIP of ₹10,000 per month for 3 years (total 36 instalments, ₹3.60 Lakhs invested).
- Instalment 1 (Month 1) compounds for the entire 36 months.
- Instalment 18 (Month 18) compounds for only 18 months.
- Instalment 36 (Month 36) has been invested for only 30 days!
If you compute CAGR using total invested capital as the "Beginning Value", you are falsely assuming that all ₹3,60,000 was deployed on Day 1. This drastically underestimates your real performance because the vast majority of your money was not yet in the market for the full 3 years.
3. What is XIRR? The Exact Cash Flow Yield
XIRR solves the Net Present Value (NPV) polynomial equation by finding the precise discount rate r that makes the sum of discounted cash inflows and outflows equal to zero:
Where CFᵢ represents the cash flow on date dᵢ, d₀ is the initial investment date, and r is the annualised XIRR.
| Feature | CAGR | XIRR |
|---|---|---|
| Cash Flow Handling | Single entry & single exit only | Multiple irregular dates & amounts |
| Best Used For | Lump-sum investments & index charts | SIPs, SWPs, STPs & real portfolios |
| Calculation Method | Closed-form algebraic formula | Numerical iteration (Newton-Raphson) |
| Sensitivity to Recent Deposits | Distorts severely if money added recently | Accurate weighting by exact days held |
4. Worked Real Example: How Misreading Returns Hurts Investors
Imagine you invested ₹10,000 every month for 5 years (60 months, ₹6,00,000 total principal). At the end of year 5, your portfolio is valued at ₹8,25,000:
Treats all ₹6 Lakhs as deployed in year 1. Misleads you into thinking your equity fund underperformed a bank FD!
Correctly weights each monthly tranche. Shows healthy, expected equity market performance.
Frequently Asked Questions
How do mutual fund apps (Zerodha, Groww, Kuvera) calculate my returns?
Modern investment platforms show two metrics: Absolute Return (useful only for horizons < 1 year) and XIRR. If your holdings are older than 1 year, XIRR is the official figure used to benchmark your performance against indices.
Can XIRR be negative?
Yes. If your current portfolio valuation is lower than the sum of your invested capital, XIRR will yield a negative annualised percentage, reflecting capital losses during market downturns.
How can I compute XIRR in Microsoft Excel or Google Sheets?
Use the formula =XIRR(values, dates). Enter all investment outflows as negative values (e.g. -10000) with their transaction dates, and enter the current portfolio market value on today's date as a positive value at the end.