SIP Calculator

What a SIP projection can and cannot tell you

A SIP projection answers one question well: given a monthly amount, a tenure, and an assumed return, what does compounding do to the money? It cannot tell you what the market will return — that input is yours, and it is the weakest one. Treat the output as a planning scenario, not a forecast, and the calculator becomes genuinely useful: it shows how sensitive your goal is to each of the three levers you actually control — how much, how long, and how aggressively you step up contributions over time.

A worked example: ₹15,000 a month for 15 years

Rohan, 30, starts a ₹15,000 monthly SIP in an equity index fund and assumes 12% annual returns. Over 15 years he invests ₹27,00,000, and the projection lands at roughly ₹75.7 lakh — ₹48.7 lakh of it growth. Two details in the year-by-year table deserve more attention than the final figure:

• Gains overtake contributions only in year 11. For the first decade, most of the corpus is simply his own money. The dramatic compounding lives almost entirely in the last third of the tenure — which is why quitting a SIP in year 6 or 7 forfeits far more than the years already invested suggest.
• The return assumption swings the outcome by lakhs. The same ₹15,000 for the same 15 years projects to ₹62.7 lakh at 10% and ₹91.9 lakh at 14%. A two-point difference in an assumption he cannot control moves the result by more than his entire first four years of contributions. Planning against a conservative band (say 10–12% for equity) and being pleasantly surprised beats anchoring on an optimistic point estimate.

Time beats amount — by more than intuition suggests

Compare two investors targeting retirement. One starts ₹15,000 a month at 25 and continues for 25 years, investing ₹45 lakh in total. The other waits a decade, then invests double — ₹30,000 a month for 15 years, ₹54 lakh in total. At the same 12%, the early starter finishes with about ₹2.85 crore; the late starter with ₹1.51 crore. Nine lakh less invested, ₹1.3 crore more at the end. Every year of delay quietly removes the most valuable years of compounding — the last ones.

The step-up feature models the realistic middle path: start with what fits today and raise the SIP as income grows. Rohan’s ₹15,000 SIP with a 10% annual step-up invests ₹57.2 lakh over the same 15 years and projects to about ₹1.30 crore — but note the honest framing: most of that improvement comes from investing more money, not from any compounding magic. The step-up’s real value is behavioural — it commits future raises before lifestyle absorbs them.

What the projection deliberately leaves out

• Costs. Expense ratios compound against you exactly the way returns compound for you. A regular plan typically carries distributor commission that a direct plan of the same fund does not; over 15 years even a half-percent drag is material. Model it by shaving your return assumption, not by ignoring it.
• Volatility.Real equity returns arrive lumpily. The projection’s smooth curve is an average; actual portfolios spend years above and below it. Rupee-cost averaging works precisely because contributions continue through the dips — pausing a SIP during a fall buys fewer of the cheapest units you were ever offered.
• Tax. Under current rules, long-term capital gains on equity funds above the annual exemption are taxed on redemption, so the corpus you see is pre-tax. Since each SIP instalment has its own purchase date, instalments from the final year may still be short-term when you begin withdrawing — sequencing redemptions matters at the goal end.

Ideas people conflate

• SIP vs lumpsum is a cash-flow question, not a returns debate. If money arrives monthly from salary, a SIP is simply how investing looks. The comparison tab matters only when a lump sum exists today — historically, deploying it immediately wins more often than spreading it, but spreading softens the regret of a crash in month two. That trade-off is about temperament as much as math — the SIP vs lumpsum guide works through both sides, including the STP middle path.
• CAGR vs absolute return.“My fund doubled” means little without the holding period: doubling in 6 years is roughly 12% CAGR; in 10 years, about 7%. The calculator speaks CAGR; fund marketing often speaks absolute.
• NAV level says nothing about value. A fund at NAV ₹15 is not cheaper than one at ₹150 — you simply hold more units of the first. Growth depends on the portfolio behind the NAV, never on the number itself.

When to come back to this page

Rerun the projection when income changes (to size a step-up), when a goal date moves, or annually to compare actual portfolio value against the scenario line — a portfolio meaningfully below the 10% curve after several years is a prompt to review fund selection or contribution levels, not to abandon the plan. Pair it with the prepay vs invest workflow if a loan competes for the same monthly surplus, or the PPF calculator to model the guaranteed-return leg of the same goal.