Lumpsum Calculator
Estimate the future value of a one-time investment, with an optional inflation check.
How it works
Enter the amount, the expected annual return and the duration in years or months. The future value is the amount grown at that return, compounded yearly. With an inflation rate entered, the future value is divided by the inflation growth over the same period to give its worth in today's money.
FV = P × (1 + r)^t
Today's value = FV ÷ (1 + inflation)^t
Real return = (1 + r) ÷ (1 + inflation) − 1Example
₹1,00,000 at 12% a year for 10 years grows to ₹3,10,585. With 6% inflation, that is worth ₹1,73,429 in today's money. The real return is 1.12 ÷ 1.06 − 1 = 5.66% a year, a real gain of ₹73,429.
Common mistakes
- Subtracting inflation from the return (12% − 6% = 6%). The real return is a ratio, (1.12 ÷ 1.06) − 1 = 5.66%.
- Reading the future value as buying power. Prices rise too, which is what the inflation-adjusted value shows.
- Entering 18 for 18 months while the unit is years. Check the Years / Months switch.
Results are estimates and are for informational purposes only.
About this calculator
Enter a one-time amount, the annual return you expect and the duration. The calculator returns the total invested, the estimated gain and the future value. The return compounds once a year; a part year uses the same exponent, so 30 months is 2.5 years.
If you also enter an inflation rate, it shows the future value in today's money and the real annual return, which is the return left after inflation. Leave inflation blank to skip those figures. Both rates are your own assumptions, and fees and taxes are not included.
Frequently asked questions
How is the future value of a lump sum calculated?
FV = P × (1 + r)^t, where r is the annual return as a decimal and t is the time in years. For ₹1,00,000 at 12% for 10 years, that is 1,00,000 × 3.1058 = ₹3,10,585.
What is the inflation-adjusted value?
It is the future value divided by (1 + inflation)^t, which expresses it in today's money. At 6% inflation, ₹3,10,585 after 10 years is worth about ₹1,73,429 today.
Why isn't the real return just the return minus inflation?
Because inflation applies to the grown amount, not to the original one. The exact figure is (1 + r) ÷ (1 + inflation) − 1, which is 5.66% for 12% and 6%, not 6%.
Do I have to enter inflation?
No. Leave the field blank and only the total invested, gain and future value are shown.
How are months handled?
Months are converted to years (months ÷ 12) and used as the exponent, so 30 months is 2.5 years of growth at the annual rate.