Compound interest and SIP calculator
Grow a lump sum, a monthly contribution, or both — with the compounding stated.
Two different questions, one page
People arrive here asking one of two things. Either "I have this much put away, what will it become" — a lump sum compounding — or "if I put this much away every month, what will I have" — a recurring contribution, which in India is usually called a SIP. They are different pieces of arithmetic and most calculators only do one, so this does both and shows their contributions separately, because seeing which half of the final number came from where changes how people think about it.
How often it compounds matters more than people expect
Twelve per cent a year compounded yearly and twelve per cent compounded monthly are not the same investment. Over ten years on a lakh, yearly compounding gives about ₹3.11 lakh and monthly gives about ₹3.30 lakh — nearly a fifth of a lakh of difference from a detail buried in the terms and conditions. The compounding frequency is a field here rather than an assumption, and the result states what was used.
Monthly money and quarterly compounding
There is a subtlety that most tools skip. If you contribute monthly but the account compounds quarterly, those two rhythms do not line up, and pretending your money starts earning the moment it lands overstates the result. This converts the compounding rate into its equivalent monthly rate first, so the contributions grow at a rate consistent with how the account actually credits interest rather than at a rate nobody offers.
Beginning or end of the month
Contributing at the start of each month rather than the end gives every instalment one extra period of growth. Over a long horizon that is not a rounding difference — it is a few per cent on the final figure, for free, just from the timing of a standing order. Both options are here.
The number almost nobody shows you
A projection that says you will have fifty lakh in twenty years is describing fifty lakh of future rupees, and future rupees buy less. Put your inflation assumption in and the result also shows what the final amount is worth in today's money. It is frequently a sobering number, and it is the one that actually tells you whether the plan works.
What a projection is and is not
This is arithmetic on the return you typed in. It is not a forecast. Market returns are not a fixed percentage delivered evenly — a fund averaging twelve per cent does so through years of thirty and years of minus fifteen, and the order they arrive in changes the outcome for anyone contributing or withdrawing along the way. Use it to compare plans, not to predict one.
Common questions
What is a SIP?
A systematic investment plan — a fixed amount invested at a regular interval, usually monthly. Set the starting amount to zero and use only the monthly field, and this becomes a SIP calculator.
Which compounding should I choose?
Whatever your account actually does. Savings accounts and most funds compound at least monthly; fixed deposits are often quarterly; some bonds are half-yearly. It is stated in the terms, and it changes the answer.
Why is the inflation-adjusted figure so much lower?
Because it is telling the truth about purchasing power. At 6% inflation, money halves in value roughly every twelve years, so a long projection loses much of its apparent size when expressed in present-day terms.
Does it account for tax?
No, and that is deliberate — capital gains treatment varies by country, by instrument and by holding period, and a single tax field would be wrong more often than right. Apply your own rate to the growth figure.
Is the return guaranteed?
No. This calculates what a steady rate would produce. Real returns arrive unevenly, and for anyone paying in monthly the order of good and bad years affects the result as well as the average.
Is my data sent anywhere?
No. It runs in your browser and answers as you type; nothing about your savings leaves the device.