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Investment Goal Calculator

Most calculators start with what you can invest and tell you where you end up. This works the other way: name the amount you want and it tells you what you would need to invest each month to get there.

Check the working

A worked example

A fixed case, for reference.

Suppose you want ₹1,00,00,000 in 15 years, assuming 12% a year, starting from nothing.

  1. Monthly rate and instalments

    i=0.01,n=180i = 0.01, \quad n = 180

  2. Compound the growth factor

    (1.01)180=5.995802(1.01)^{180} = 5.995802

  3. Annuity-due factor: what ₹1 a month grows to

    5.995802−10.01×1.01=504.576\frac{5.995802 - 1}{0.01} \times 1.01 = 504.576

  4. Divide the target by that factor

    1,00,00,000504.576=19,818\frac{1{,}00{,}00{,}000}{504.576} = 19{,}818

About ₹19,818 a month. You would contribute roughly ₹35.7 lakh across 180 instalments; the remaining ₹64.3 lakh comes from the assumed growth. Notice how much of the goal the return is doing — and therefore how much the plan depends on that assumption holding.

The formula

P=T−E(1+i)n(1+i)n−1i×(1+i)P = \frac{T - E(1+i)^{n}}{\frac{(1+i)^{n} - 1}{i} \times (1+i)}

The SIP annuity formula rearranged for the instalment, after subtracting what existing savings will grow to on their own.

i=r1200n=y×12i = \frac{r}{1200} \qquad n = y \times 12

Monthly rate and number of instalments.

What each symbol means

P
the monthly investment required
T
the target amount
E
existing savings already earmarked for this goal
i
the monthly rate
n
the number of monthly instalments

What this assumes, and where it stops

Assumptions

  • The return you enter is earned steadily, every month, for the whole tenure. Real markets do not behave this way — the same average delivered in a different order produces a different result.
  • The instalment stays the same every month for the whole period. A step-up SIP would let you start lower — try the Step-Up SIP calculator.
  • Existing savings are invested at the same assumed rate as the new instalments.
  • The target is in future rupees. If you set it in today’s money, use the Inflation calculator first to find the equivalent future figure.

Limitations

  • Setting a target in today’s money is the most common mistake with this calculator. A goal of ₹1 crore in 15 years is worth about ₹41 lakh in today’s terms at 6% inflation.
  • Taxes are not modelled. Capital gains tax on redemption reduces what you actually receive.
  • Costs are not modelled: expense ratio, exit load, and any transaction charges all reduce real returns.
  • If the required instalment is unaffordable, the honest options are a longer horizon, a smaller target, or a step-up plan — not a higher assumed return.
  • This is a projection from a fixed assumption, not a forecast. Returns vary year to year and can be negative for long stretches.

What this calculator does

  • Calculates the monthly investment required to reach a target amount.
  • Credits any existing savings, which keep growing on their own and reduce what you need to add.
  • Separates how much of the target you contribute from how much the assumed return provides.

Common questions

Related calculators

Different questions about the same money. These use the same conventions, so the numbers are comparable.

  • SIP Calculator

    Project what a monthly SIP could grow to over time, and see how much of the total is your own contribution versus assumed returns.

  • Step-Up SIP Calculator

    Model a SIP that increases every year, which is what usually happens as income grows, and see the difference against a flat SIP.

  • Inflation Calculator

    Find what a sum today is worth in future purchasing power, and what a future target costs in today’s money.