How to use the investment calculator
- Enter a starting amount, a monthly investment, or both. Monthly investing is often called a SIP (systematic investment plan) in India.
- Enter the yearly return you want to assume and how long you'll invest.
- Optionally, raise your monthly investment each year (a step-up) and add inflation to see the result in today's money.
Every result here is an estimate. It shows what would happen if your investments grew by exactly the same amount every year. Real markets don't behave like that.
How the estimate is calculated
Monthly return = (1 + yearly return)1/12 − 1
Each month: Balance = Balance × (1 + monthly return) + Monthly investment
Value in today's money = Final value ÷ (1 + inflation)years
The yearly return is turned into an equivalent monthly return, so that 12 months of growth add up to exactly the yearly figure you entered. With no step-up, this matches the standard future value formula for a lump sum plus regular monthly payments.
Worked example
You invest 5,000 now and 300 a month for 20 years, assuming 8% a year.
You put in 77,000 in total. The estimated value is 194,004.51, so 117,004.51 is estimated growth. With 3% yearly inflation, that's worth about 107,415.59 in today's money.
If you also raise the monthly amount by 5% each year (ending at about 758 a month), you invest 124,037.43 and the estimated value rises to 272,934.88.
What return should I use?
There's no right number, because no one knows future returns. Many people try a few rates to see a range, for example a cautious, a middle and a hopeful figure. Long-run averages for share-based funds have historically been higher than for cash or bonds, but with much bigger ups and downs, and past performance doesn't guarantee future results. Remember to allow for fund fees, which come out of your return.
Lump sum or monthly investing?
Investing a lump sum earlier gives it more time to grow, if markets rise. Investing monthly spreads your purchases over time, which smooths out the effect of buying at a high point, and suits people investing from their income. Many people do both.
Frequently asked questions
How is this different from the compound interest calculator?
The compound interest calculator is for savings with a fixed interest rate and a set compounding frequency. This one is for investments where you assume an average yearly return, and it adds a yearly step-up and an inflation adjustment.
Does this include tax and fees?
No. Fund fees, platform charges and taxes on gains or income all reduce what you keep. Lower your expected return to allow for them, for example by 0.5–1% for typical fund fees.
Can my investment lose money?
Yes. Investments like shares and funds can fall in value, sometimes for years, and you may get back less than you put in. This calculator can't show that risk; it assumes a steady return.
Is this financial advice?
No. It's a planning tool to explore scenarios. For decisions about your own money, consider speaking to a regulated financial adviser.
Formulas checked 29 October 2026. This calculator is for planning and education, not financial, tax or legal advice.