Lumpsum Investment Calculator

The calculator uses annual compounding: maturity value = amount × (1 + annual return)^years, with the return applied once at the end of each year. With the default inputs (₹1,00,000 at 12% for 10 years) the maturity value is about ₹3,10,585, so the estimated gain is about ₹2,10,585.

Annual compounding fits returns quoted as a yearly average (CAGR), which is how fund performance is usually reported. It slightly understates products that compound more often. A 5-year deposit at 7.5% shows about ₹1,43,563 here, while the FD calculator with quarterly compounding shows about ₹1,44,995 for the same rate. For bank or post office deposits, use the FD calculator; for anything quoted as an annual average return, this one is the right fit.

A quick check on any result is the rule of 72: divide 72 by the return to get the years needed to double your money. At 12%, that is 6 years; the exact figure is about 6.1 years.

Here is ₹1,00,000 invested once and left alone, at four return assumptions:

Two patterns stand out. First, most of the growth arrives late: at 12%, the money grows by about ₹2.1 lakh in the first 10 years and by about ₹13.9 lakh in the next 15. Second, the gap between return assumptions widens with time. Over 5 years, 8% and 12% differ by about ₹29,000; over 25 years, by more than ₹10 lakh. That is why the return you enter matters most for long horizons.

For fixed-income products, enter the rate the product states. As a reference, the 5-year post office time deposit pays 7.5% for the October–December 2026 quarter.

For market-linked investments such as equity or hybrid funds, there is no fixed rate. Returns vary from year to year and can be negative over short periods, so any figure you enter is an assumption, not a promise. A practical approach:

• Run three cases, for example 8%, 10% and 12%, and note all three results.
• Base decisions on the lowest case, and treat anything above it as a bonus.
• Use a return after costs. Fund expenses come out of returns every year, and the calculator does not deduct them.
• Match the horizon to the risk: a lumpsum you need in 2 or 3 years should not depend on a high equity return.

The result is in future rupees. If prices rise every year, ₹3,10,585 in 10 years will buy less than ₹3,10,585 buys today. To see the value in today's money, use a real return in place of the expected return:

real return = (1 + expected return) ÷ (1 + inflation) − 1

Assume, purely for illustration, 6% inflation. With a 12% expected return, the real return is about 5.66%. Enter 5.66% and the calculator shows about ₹1,73,429 after 10 years: that is what your maturity value is worth in today's prices. The same logic works in reverse for goals. A cost that is ₹5 lakh today will be higher when you need the money, so inflate the goal before you work out how much to invest.