How to Calculate Return on Investment (ROI)

Aneesh bought gold at ₹3,000 per gram. Today it's ₹6,000. His friend's mutual fund doubled in three years. Ask either "what was your return on investment?" and both will happily say "100%." Ask them to compare those two results fairly — and the simple ROI figure suddenly isn't enough. ROI answers "how much did I make," while smarter metrics answer "how well did I use my time." This post fixes both skills.

The basic ROI formula

ROI expresses investment performance as a percentage of what you put in:

ROI = (final value − initial cost) ÷ initial cost × 100

Worked example: you invest ₹1,00,000 and the position grows to ₹1,50,000:

ROI = (1,50,000 − 1,00,000) ÷ 1,00,000 × 100 = 50%

Simple, universal, and dangerously easy to compare out of context. A 50% in two years is excellent; a 50% in twelve years is mediocre. That missing ingredient — time — is why raw ROI alone can mislead you.

Why time has to be in the number

Consider two real scenarios for the same ₹1,00,000:

Investment	Final value	Total ROI	Period	Annualized ROI
Fixed deposit	₹1,40,255	~40%	5 years	7%
Equity fund	₹1,50,000	50%	5 years	~8.4%

The equity fund "won" by 10 points of headline ROI. But annualized, the true gap is only ~1.4 points a year — and if your money was locked away for the whole period, the FD's guaranteed 7% versus the fund's uncertain 8.4% suddenly looks like a much closer race.

Annualized ROI (CAGR) — the honest metric

Spread any return over its holding period with the compound-annual-growth-rate formula:

Annualized ROI = (final value ÷ initial cost)^(1/years) − 1, then × 100

Worked example: that 50% over 5 years:

(1.5)^(1/5) − 1 ≈ 0.0844 → 8.4% per year

This is the figure to use when comparing a 2-year stock position against a 5-year FD against a 10-year property — and it's also the reason Indian investors use tools like XIRR for SIPs: when cash flows in over years rather than at one moment, the annualized return is computed across periodic contributions, giving a "what did MY money actually earn per year" number.

ROI ignores taxes and inflation — fix that too

A return quoted as "8%" can become ~5% after tax and ~3% after inflation, so real-world ROI needs two adjustments:

• Tax. FD interest lands at your slab rate; equity LTCG above the exemption is taxed at a concessional rate. Compute ROI before tax, then subtract the tax you'd actually pay.
• Inflation. Real ROI ≈ nominal ROI − inflation. A "7% — nothing" FD in a 6% inflation year is barely protecting principal.

Practically: prefer the metric that matches the comparison. Raw ROI for a single holding over a single period; annualized (CAGR) for anything multi-year; XIRR for anything with recurring or irregular cash flows such as SIPs.

Common mistakes

• Comparing total ROI across different durations. A 50% in two years vs 50% in five years — the first is ~22.5% annualized, the second ~8.4%. Different league entirely.
• Ignoring the currency-anchored cost of holding. Annualized ROI doesn't price in inflation or taxes unless you subtract them.
• Confusing ROI with profit margin. ₹50,000 gain on ₹1,00,000 is 50% ROI; if your business required ₹5 lakh of working capital for the same profit, that's a different 10% ROI conversation.
• Excluding transaction costs. Brokerage, exit loads, and stamp duty shrink the true numerator. Include them.

Key takeaways

• ROI = (final − cost) ÷ cost × 100.
• Always add the time dimension via annualized ROI (CAGR) when comparing different holding periods.
• Subtract taxes and inflation to see the real return you keep.
• For recurring investments (SIPs), use XIRR, not a flat ROI.

Frequently asked questions

Is a higher ROI always better? Without adding risk, tax and time, no. A guaranteed 7% can beat a risky headline 9% once risk and volatility are priced in.

What's the difference between ROI and IRR/XIRR? ROI is a point-in-time comparison of money in vs money out. IRR/XIRR account for when money moved — essential for SIPs and lumpy real-estate inflows.

How do I apply this to my portfolio? Start with individual holdings, annualize each, and weight them by amount. Model your own comparisons — including how a compounding path changes results — with the ROI Calculator, and see how long-term growth stacks up with the Compound Interest Calculator.