SIP Calculator

Filling it in

1. Monthly investment takes whatever you can genuinely commit each month. It steps in hundreds, and the 1,000 already sitting there is only a starting point.
2. Expected annual return is a percent per year and moves in steps of 0.1. Time period is two boxes side by side: years, plus a months box between 0 and 11 for horizons that stop partway, like 2 years and 6 months.
3. Read the answer. Maturity value is the figure, with Total invested and Estimated returns as the two cards under it, and they change as you type; there is nothing to press. A term too short to reach the turning years gets a note saying which years it stops short of.

About this tool

Fifteen years of 1,000 a month at 12% lands at 504,576.00. Only 180,000 of that is money you handed over. The remaining 324,576.00 is what the compounding did, and that split is what a SIP calculator is really for. Those are the figures the page opens on, and every box redraws the answer while you type. Two years in that run matter more than the rest: in year 7 one year's growth first passes that year's deposits, and in year 11 the whole of the growth passes the whole of what you paid in. The page names both and marks them on the chart.

The formula underneath is the future value of an annuity due. Each month's money is treated as arriving on the first, before that month's growth is applied, and the annual rate you type gets divided by twelve to give the monthly one. A 12% assumption therefore compounds at 1% a month, 180 times across fifteen years. Every deposit earns from the month it lands until the end of the term, which is why stretching the horizon moves so much of the total out of your column and into the returns column.

Below the answer sits a chart with two tabs. Breakdown stacks what you paid in that year against what that year earned, one bar per year. Balance draws the running total as a line, and either hovering or walking it with the arrow keys reads out the figure at any point. Show year-by-year schedule opens the same numbers as a table, and Download CSV saves them as sip-growth-schedule.csv if you want to keep the working.

The return box is where the honesty lives. Twelve percent is the number everyone types, and nobody owes it to you. Real funds also refuse to pay out in the smooth monthly line this model assumes. So run it twice: once at the rate you are hoping for, once two or three points under, and let the second answer set the plan. On 5,000 a month for fifteen years, 12% projects 2,522,880.00 and 9% projects 1,906,219.06. Identical discipline, six hundred thousand apart.

One thing the results deliberately leave off is a currency symbol. Figures come back as plain numbers to two decimal places, so the page works for rupees as readily as for dollars, provided you keep your own units straight. The monthly amount, the rate and the term are written into the page address as you type. Bookmark it and the same projection comes back.

Good to know

• Everything here is gross. The expense ratio, the exit load and the tax on your gains all sit outside the model, and so does inflation, which leaves the maturity value denominated in future money rather than today's.
• A step-up SIP has nowhere to go on this page. If your contribution climbs each year, as it tends to once a salary moves, the real total finishes above what you see. Running it at the average of the amounts you expect gets you reasonably close.
• A constant return is a modelling convenience. A real fund hands you a bad three years and a good one in an order nobody can know in advance, and with money going in every month that order changes the end figure even when the average comes out the same.