Goal SIP calculator: how much to invest every month

Your goal is priced in today's rupees, and you will pay for it in future ones

Almost every goal starts as a sentence: I want ₹50 lakh for my daughter's education in fifteen years. It is a perfectly sensible sentence, and it contains a quiet mistake. The ₹50 lakh is a figure you arrived at by looking at what that education costs now. The bill, however, arrives in fifteen years, denominated in the rupees of that year.

At 6% general inflation — and education inflation in India has usually run hotter than general inflation, not cooler — that ₹50 lakh becomes about ₹1.2 crore. Not because the course got better, but because the rupee got smaller. So the honest question is never "what monthly SIP reaches ₹50 lakh", it is "what monthly SIP reaches ₹1.2 crore".

The difference is not a rounding error. Solve for ₹50 lakh over fifteen years at a 12% assumed return and you get roughly ₹9,900 a month. Solve for the ₹1.2 crore the goal will actually cost and you get roughly ₹23,700. The first number is less than half the second, and it feels comfortable, which is precisely what makes it dangerous. Someone paying ₹9,900 a month with real discipline for fifteen years does everything right and still arrives with roughly 40% of what they need — and finds out at the worst possible moment, when the fee is due. That gap is the whole reason this calculator exists, and why it shows both answers side by side instead of quietly picking the flattering one.

Years do more work than rupees

The single strongest lever in this calculation is not the amount you invest. It is how long the money gets to sit there. Compounding is exponential in time and merely linear in contribution, so the rupees you invest first do a wildly disproportionate share of the lifting.

Take a ₹1 crore goal in today's money, 6% inflation, 12% assumed return, nothing saved yet. Over 25 years the goal inflates to about ₹4.3 crore and needs roughly ₹22,600 a month. Over 15 years it inflates to about ₹2.4 crore and needs roughly ₹47,500. Over 10 years, about ₹1.8 crore and roughly ₹77,000 a month.

Now look at what actually leaves your bank account. The 25-year investor contributes about ₹68 lakh in total and ends with ₹4.3 crore. The 10-year investor contributes about ₹92 lakh — a quarter more money — and ends with ₹1.8 crore. They saved harder, longer hours, more sacrifice, and finished with less than half as much. Nothing separates them except fifteen years of compounding. This is why "start now with whatever you can" is better advice than "wait until you can afford to do it properly", and it is the one part of the plan you can never buy back later.

Some goals have no business being funded this way

The maths above assumes your money grows at a steady rate every single month. It does not. Equity returns arrive in violent, uneven bursts, and the average only shows up if you stay long enough for the bursts to average out. Over twenty years that is a reasonable bet. Over two years it is not a bet at all, it is a coin toss with your down payment on it.

The problem is sequence risk: it is not the average return that gets you, it is when the bad years land. A 30% drawdown in year eighteen of a twenty-five year plan is an inconvenience you have time to recover from. The same drawdown four months before you pay a hospital or a college is a catastrophe, because there is no time left. A short horizon has no recovery capacity, and no calculator can give it one.

So, directionally: anything you need within roughly three years does not belong in equity. Emergency funds, a wedding next winter, a car this year, next year's school fees, a home down payment with a signed date on it — those belong in instruments where the maturity value is known in advance and the capital does not move. Fixed and recurring deposits, liquid and short-duration debt options, and plain savings. You will earn less. That is the fee for certainty, and on a short horizon certainty is the thing you are actually buying. Use this calculator for the five, ten and twenty year goals; use the FD and RD calculator for the near ones.

The return assumption is doing most of the work

Drag the return slider and watch the monthly figure move. It moves more than anything else on the page, which should tell you how much weight a single unverifiable number is carrying. On a ₹1 crore nominal goal twenty years out, 12% asks about ₹10,000 a month; 6% asks about ₹21,500. Halve the return and the required contribution roughly doubles.

That asymmetry matters because of which way the error runs. If you plan at 12% and get 14%, you finish early — a pleasant problem. If you plan at 12% and get 8%, you arrive at the deadline substantially short, with no time left to fix it. The optimistic assumption does not just risk being wrong; it fails in the direction that cannot be recovered from.

So run the number you hope for, then run it four or five points lower and look at that monthly figure honestly. If the pessimistic version is affordable, you have a plan. If it is only affordable at the optimistic return, you do not have a plan — you have a hope with a spreadsheet attached. The fix is not a better assumption, it is more years, a smaller goal, or a contribution that rises over time.

Doing this against your actual money

A calculator gives you a number. Whether that number survives contact with your salary is a different question, and it is answered by tracking, not by arithmetic. Klera has savings goals and a SIP calculator built in, both fully offline — you can set the goal, put the monthly figure against a budget with alerts when you drift, track the SIP itself with real XIRR rather than an assumed return, and see the whole thing roll up into net worth alongside your other holdings. No account, no cloud, nothing leaves the phone; it is AES-256 encrypted on the device. It is free on Android, and it does not have live market data or tax calculators — it works from the numbers you enter.

What this model leaves out

Four things, and all of them matter. First, tax. The figures above are pre-tax; equity gains are taxed on redemption, so the corpus you can actually spend is smaller than the corpus shown. If the goal is a real bill, aim somewhat above the target rather than exactly at it.

Second, the smooth curve. The chart draws a tidy line because the maths applies the same monthly rate every month. Reality is jagged, and your corpus will spend long stretches above and below that line. Judge the plan by the destination, not by where you are in year seven.

Third, everything changes. Your income will rise, which makes a flat monthly contribution progressively easier and probably too conservative — a step-up usually matches real life better. The goal will change too. Recalculate once a year rather than treating a number you produced in 2026 as binding for fifteen years.

Fourth, the model assumes you never miss a month. Nobody manages that. Missed contributions early cost far more than missed contributions late, for the same reason early rupees are worth more — so if something has to give, give it up in the final years, not the first ones. And if you have already invested towards this goal, put it in the "already saved" field: existing money that has been compounding for years is doing more work than any monthly figure you can start today.