Understanding Investment Returns: CAGR, XIRR, ROI and More

Why "What's My Return?" Is a Trickier Question Than It Sounds

Ask any investor what return they've earned, and most will do quick mental math — subtract what they put in from what it's worth now. But that simple math hides a lot: how long the money was invested, whether it went in all at once or in pieces, and which of several very different metrics is actually being used. This guide walks through the core concepts — from basic interest to CAGR, XIRR, ROI, and dividend yield — that together answer "what's my real return" properly.

Starting Point: Simple Interest vs Compound Interest

Every return calculation eventually traces back to one basic idea — does your money earn returns only on the original amount, or on the original amount plus everything it's already earned? Simple interest only grows the principal; compound interest lets returns earn their own returns, which is why compounding is often called the most powerful force in personal finance. Small differences in rate or time horizon compound into surprisingly large gaps over long periods.

For the full breakdown — including a side-by-side numeric comparison — see Simple Interest vs Compound Interest: What's the Real Difference?

Future Value: Turning "Investing Today" Into "Worth This Much Later"

Once compounding is understood, the natural next question is: what will a specific investment actually be worth at a future date? That's exactly what Future Value (FV) calculates — whether it's a one-time lump sum or a monthly SIP. Three levers drive every FV number: amount invested, rate of return, and time — and of these three, time tends to matter more than most people expect, since it's the one lever that's hardest to make up for later if you start late.

Full formulas, a worked SIP example, and the most common future-value mistakes are covered in Future Value Explained: How Money Grows Over Time.

CAGR: The Number Most People Mean When They Say "Return"

CAGR (Compound Annual Growth Rate) answers a very specific question: if a lump-sum investment grew smoothly at a constant annual rate from its starting value to its ending value, what would that rate be? It smooths out the year-to-year bumps of an actual investment into a single, comparable annual figure — which is exactly why it's the standard way to compare a mutual fund's 5-year performance to another fund's, or to an FD's stated rate.

The complete explanation, formula, and common misuses are in What Is CAGR and Why It's the Number You Should Trust Most.

XIRR: What CAGR Can't Handle — Real-World SIPs

CAGR has one major limitation: it assumes one lump sum invested at one point in time. But most retail investors in India invest through SIPs — money going in monthly, each installment with a different amount of time to grow. XIRR (Extended Internal Rate of Return) is built specifically for this, correctly weighing each cash flow by its exact date rather than treating all money as if it went in on day one.

A full worked SIP example, and a clear rule for when to use which metric, is in XIRR vs CAGR: When to Use Which.

Stock ROI: Why Price Gain Alone Isn't the Full Story

For individual stocks, there's a common shortcut mistake — comparing purchase price to current price and calling the difference "the return." That misses dividends received along the way and brokerage/transaction costs paid — both of which are part of the real total return. A stock's genuine ROI is price gain plus dividends minus costs, annualized using CAGR or XIRR depending on how it was bought.

A full worked example showing how much dividends alone can add to a return figure is in How to Calculate Your True Stock Market Return (ROI).

Dividend Yield: A Useful Number That's Often Misread

Dividend yield tells you how much dividend income a stock pays relative to its current price — nothing more. Because price sits in the denominator, yield can rise simply because a stock's price has fallen, not because the company is paying more. This is the classic "yield trap," where an attractively high yield actually signals a struggling stock rather than a generous one.

The full formula, worked example, and how to tell a genuine high yield from a trap, are covered in Dividend Yield Explained: What It Tells You (and What It Doesn't).

How These Metrics Fit Together

Key Takeaway: Every one of these metrics answers a slightly different question — knowing which one applies to your specific situation (lump sum vs SIP, price-only vs total return) is what turns a confusing percentage into a number you can actually trust and act on. The next part of this series covers something just as important: how to fairly compare these returns across completely different types of investments, and why your app's displayed return might not tell the full story.

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