SIP Calculator

The calculator treats every SIP instalment as invested on the first day of the month. It divides your expected annual return by 12 and compounds it every month, so the first instalment grows for the full period and the last one grows for a single month. Total invested is simply the monthly amount × 12 × years, and estimated returns are the maturity value minus that.

With the defaults (₹10,000 a month, 12%, 10 years) you invest ₹12,00,000 and the maturity value comes to about ₹23,23,391. Some calculators assume the money goes in at the end of each month instead. On the same inputs that method gives about ₹23,00,387, roughly ₹23,000 less, so a small gap between two SIP calculators usually comes from this timing choice, not an error.

Fund factsheets and apps report returns as an annualised figure (CAGR, or XIRR for SIPs). This calculator does something slightly different: 12% entered means 1% a month, and 1% compounded for 12 months works out to about 12.68% a year.

So if you want to project a fund that has delivered 12% a year, convert it first:

rate to enter = ((1 + annual return)^(1/12) − 1) × 12 × 100

For 12%, that is about 11.39%. On the default ₹10,000 for 10 years, entering 11.39% gives about ₹22,40,816, around ₹82,575 below the figure at 12%. The gap grows with the period, so it matters most for 20- and 25-year plans.

The calculator is most useful for comparing your own options side by side. Take a ₹8,000 SIP at an assumed 12%:

Waiting five years roughly halves the result. To catch up by the same date you would need almost double the monthly amount, and you would put in about ₹9.3 lakh more of your own money.

The reverse case is stopping early. If you invest ₹8,000 for 10 years (₹18,58,713 at the end) and then leave the money invested, entering ₹18,58,713 in the lumpsum calculator at 12% for another 10 years shows about ₹57,72,880. The lumpsum tool compounds yearly, so this is a slightly cautious figure.

The calculator keeps the same amount every month for the whole period. Real plans rarely do, so build the picture in pieces:

• A pause of a few months: run the plan with the period you will actually invest, then treat the paused months as a small shortfall. There is no field for skipped instalments.
• A planned yearly increase: use the step-up SIP calculator, which raises the amount every 12 months.
• A one-time top-up: run it through the lumpsum calculator for the years it will stay invested, and add the two results.
• Fund costs: reduce the return you enter by the fund's expense ratio, because the calculator deducts nothing.

Market-linked returns also arrive unevenly. A fall in the final years hurts far more than one early on, because by then most of the corpus is in the fund. Plan for the target with a lower return than you hope for, and keep the last few years' money somewhere less volatile if the date is fixed.