Complete guide
Reviewed July 2026A lumpsum investment is a single, one-time deposit that you leave to grow — the opposite of a SIP's monthly drip. When you receive a bonus, an inheritance, a maturity payout or sale proceeds, the question is what that one amount could become if invested and left alone.
This calculator answers it with the compound-growth formula: enter the amount, the expected annual return and the number of years, and it returns the maturity value and the wealth gained. Because there are no further contributions, the entire result is driven by two forces — your rate of return and, far more powerfully, time.
Below: the formula, worked examples, a year-by-year growth illustration, the crucial lumpsum-vs-SIP comparison, and the mistakes that lead to disappointment.
The lumpsum formula
FV = P × (1 + r)^n P = principal (the one-time investment) r = expected annual return (decimal) n = number of years Wealth gained = FV − P
This is pure compound interest. Unlike a loan or a SIP, there's only one cash flow, so the maturity value is simply the principal grown by (1 + r) once per year for n years. Every extra year multiplies the whole balance again — which is why the curve bends upward steeply near the end.
Worked example
- Invest ₹5,00,000 at an expected 12% for 15 years.
- FV = 5,00,000 × (1.12)^15 = 5,00,000 × 5.4736 = ₹27,36,780.
- Wealth gained = 27,36,780 − 5,00,000 = ₹22,36,780 — over 4× the original.
- Extend to 20 years: 5,00,000 × (1.12)^20 = ₹48,23,147 — the extra 5 years alone add ₹21 lakh.
- That last observation is the whole point: the final years contribute the most, because compounding acts on the largest balance.
| Return | 5 years | 10 years | 15 years | 20 years |
|---|---|---|---|---|
| 8% | ₹1.47 L | ₹2.16 L | ₹3.17 L | ₹4.66 L |
| 10% | ₹1.61 L | ₹2.59 L | ₹4.18 L | ₹6.73 L |
| 12% | ₹1.76 L | ₹3.11 L | ₹5.47 L | ₹9.65 L |
| 15% | ₹2.01 L | ₹4.05 L | ₹8.14 L | ₹16.37 L |
Lumpsum vs SIP
The two aren't rivals — they suit different situations. A lumpsum puts all your money to work immediately, so in a rising market it usually out-earns the same total drip-fed as a SIP (which holds cash back to invest later). But a lumpsum also carries timing risk: invest it all the day before a crash and you feel the full drop. A SIP averages your entry price and smooths that risk.
| Lumpsum | SIP | |
|---|---|---|
| Cash flow | One-time | Monthly |
| Market timing risk | Higher (all in at once) | Lower (averaged) |
| Best in | Rising markets, when you have the cash | Volatile markets, from salary |
| Discipline needed | One decision | Ongoing automation |
| Typical use | Bonus, inheritance, windfall | Regular income |
Using this calculator
- Enter the one-time amount you're investing.
- Set a realistic expected return — 10–12% is a conservative long-run assumption for diversified equity; use lower for debt.
- Choose the horizon; lumpsums reward long holding periods disproportionately.
- Read the maturity value and wealth gained, and note how much the last few years contribute.
Common mistakes
- Assuming a recent bull-market return (18%+) continues — plan conservatively and treat upside as a bonus.
- Investing a lumpsum you might need soon; equity needs 5–7+ years to ride out volatility.
- Panic-selling after investing just before a dip — the lumpsum's advantage only materialises if you stay invested.
- Ignoring inflation: ₹27 lakh in 15 years buys far less than today; sanity-check goals in real terms.
- Forgetting tax on gains at redemption, which reduces the net maturity value.
Frequently asked questions
Glossary
- Lumpsum
- A single, one-time investment left to grow.
- Future value (FV)
- What the investment becomes after compounding for n years.
- Compound growth
- Growth where each year's return is earned on the whole accumulated balance.
- STP
- Systematic Transfer Plan; moving a lumpsum into equity gradually to reduce timing risk.
- Timing risk
- The risk of investing a lumpsum just before a market decline.
- Nominal vs real
- Nominal value ignores inflation; real value reflects purchasing power.
- LTCG
- Long-Term Capital Gains; the tax on gains from long-held investments at redemption.
- Expected return
- The assumed annual growth rate; an estimate, not a guarantee.
Key takeaways
A lumpsum grows by FV = P x (1 + r)^n; one deposit, then pure compounding. Its power is time: the final years add the most because they compound the largest balance. Lumpsum beats SIP in rising markets but carries timing risk a SIP averages away; splitting a windfall via an STP is the pragmatic compromise. Plan returns conservatively, stay invested for 7+ years, and check goals in inflation-adjusted terms.
Enter your amount, return and horizon above; then extend the years by five and watch how much the final stretch alone adds.