Investment calculator (dynamic)

Why a phased investment calculator

A career usually has three stages that matter for a long saving plan: a slow start when the salary is small, a middle stretch when the salary is bigger and a bonus turns up once a year, and a later stretch when the income is highest but the time left to compound is shortest. A single-rate, single-SIP tool like the SIP calculator cannot show all three in one run. This page runs each stretch as its own phase, carries the closing balance forward, and adds up the lot.

The arithmetic is the same inside every phase. What changes from phase to phase is the starting lump sum, the monthly SIP, the assumed annual return and the number of years. Nothing is hidden. Each phase is a row in a table you fill in.

The formula each phase uses

Inside a phase of y years and an assumed rate r, the monthly rate is r divided by 12 and the phase runs for twelve times y months. On the first month of the phase the lump sum is added once, before anything else. Every month, in order: the SIP is added, and one month of return is applied to the new balance. In symbols the running balance is new balance equal to opening balance plus SIP, multiplied by one plus monthly rate.

At the end of the phase the closing balance becomes the opening balance of the next phase. The SIP, the rate and the years can all change at that point, but nothing resets. A reader who leaves the SIP at zero in a phase gets pure lump-and-compound behaviour for that stretch, which is useful for a sabbatical or a windfall that then grows on its own.

Worked example you can check by hand

The default run is a three-phase plan over twenty years, meant to feel like a real career. Phase one is five years of a ₹10,000 monthly SIP after a ₹1,00,000 opening lump, at an assumed 12 per cent. That phase closes at about ₹10,06,533 on ₹7,00,000 put in. Phase two takes the closing balance, adds ₹50,000 and raises the SIP to ₹20,000 a month for five more years at an assumed 10 per cent, closing at about ₹32,99,971 on cumulative ₹19,50,000 contributed. Phase three stops adding lump sums, lifts the SIP to ₹30,000 a month for ten years at an assumed 8 per cent, and finishes at about ₹1,28,49,719 on a total of ₹55,50,000 invested across the full twenty-year window.

Of the final value, ₹55,50,000 is your own money and ₹72,99,719 is the return built up at the assumed rates. The last phase carries the heaviest arithmetic because it starts with the largest opening balance and runs for the most years.

How each input moves the answer

Years is the largest lever. Dropping the third phase from ten years to seven, and leaving everything else as above, lowers the final value from about ₹1,28,49,719 to roughly ₹91,52,265, because the closing balance of phase two has three fewer years of compounding on top of the smaller cumulative contribution. Rate is the second lever, and its effect is non-linear in the long phase. Raising the last phase from an assumed 8 per cent to an assumed 11 per cent on the same twenty-year plan lifts the final value to about ₹1,64,33,727 even though the money put in is unchanged.

Changing a lump sum is the smallest lever, because it is a one-off. Removing the ₹50,000 start-of-phase-two lump cuts the final value by about ₹1,82,600 on the default plan. SIPs move the answer much more than lump sums when the phase is long enough for the stream to matter.

Where this page agrees with the other NIFM tools

Setting a single phase with any years, lump sum, monthly SIP and rate reproduces the number from the SIP calculator plus a lump-and-compound add-on, because the convention is the same on both pages: start-of-month instalments and a monthly rate equal to the annual rate divided by twelve. Setting zero SIP and a positive lump reduces to a pure lump-sum run that matches the lump sum calculator. For a step-up pattern where the instalment rises once a year, use the step-up SIP calculator instead, because this page does not step a SIP within a phase.

The assumed return still sets the range

The rate on each phase is a figure you supply. Mutual fund and equity returns move from year to year, and no real plan will earn the same rate every month. Treat the final value as an arithmetic result at the rates and inputs on the screen, and run a lower-rate case before leaning on the answer. On the default plan, taking two percentage points off every phase (10 per cent, 8 per cent, 6 per cent) pulls the final value down to about ₹1,03,30,487 on the same contributions.

Past returns of a scheme appear in its fact sheet and Scheme Information Document. They describe what has happened and carry no promise about what the future will be.

What this calculator leaves out

• Tax on redemption. Each phase's closing balance is a pre-tax figure. The mutual fund returns calculator works on actual cash flows, and the tax position depends on the fund type and holding period of each unit.
• Inflation. To restate the final value in today's money, use the inflation calculator.
• A step-up within a phase. The SIP is flat inside each phase; to raise the instalment every year, use the step-up SIP tool or split the stretch into shorter phases.
• Fees charged by the product. To see the drag of an annual fee on a lump-sum investment, switch to the fee drag mode of the asset management calculator.
• Any withdrawal. Once withdrawals begin, the SWP calculator is the right tool.

A plan is a draft, not a forecast

The numbers on this page are arithmetic on the figures you entered. They are useful for comparing one plan to another, for sizing a contribution against a goal, and for seeing how the closing balance at the end of one phase sets up the next. They are not a forecast of what any real investment will produce. The page never fetches prices and never stores anything. If a plan reads well here, that is a prompt to read the scheme documents of the products you intend to use and to put the plan in front of a qualified adviser before committing money.

Frequently asked questions

Courses that teach the subject behind the investment calculator (dynamic)