SIP Calculator

SIP Calculator: Turn Small Monthly Investments Into Long-Term Wealth

A Systematic Investment Plan (SIP) is a way of investing a fixed amount into a mutual fund at regular intervals, usually every month, instead of putting in a large lump sum at once. This calculator estimates the future value of your monthly SIP so you can see how a modest, disciplined contribution can grow into a meaningful corpus over time. It is built for salaried professionals, first-time investors, parents saving for a child's education, and anyone who wants to plan a goal such as a house down payment or retirement without trying to time the market.

The core idea a SIP relies on is the power of compounding: your returns earn further returns. Because you invest every month, you also benefit from rupee-cost averaging — you buy more units when markets are low and fewer when they are high, which smooths out your average purchase price over the years.

The Formula in Plain Words

This tool uses the standard future value of an annuity-due formula, which assumes each contribution is made at the start of the period (the convention most Indian SIP calculators follow):

FV = P × (((1 + i)^n − 1) / i) × (1 + i)

• P is your fixed monthly investment amount in rupees.
• i is the monthly rate of return, i.e. the expected annual return divided by 12. For 12% a year, i = 0.12 / 12 = 0.01.
• n is the total number of monthly instalments (years × 12).

In words: take one plus the monthly rate, raise it to the power of the number of months, subtract one, divide by the monthly rate, multiply by one plus the monthly rate, and finally multiply by your monthly instalment. The result is the estimated maturity value.

A Fully Worked Example

Suppose you invest Rs. 10,000 every month for 10 years at an expected return of 12% per year.

• Monthly investment, P = Rs. 10,000
• Monthly rate, i = 0.12 / 12 = 0.01
• Number of months, n = 10 × 12 = 120

Step 1: (1 + i)^n = (1.01)^120 ≈ 3.3004.

Step 2: (3.3004 − 1) / 0.01 = 2.3004 / 0.01 = 230.04.

Step 3: 230.04 × 1.01 = 232.34.

Step 4: 232.34 × Rs. 10,000 ≈ Rs. 23,23,400 (about Rs. 23.23 lakh).

You would have actually invested only Rs. 10,000 × 120 = Rs. 12,00,000 (Rs. 12 lakh). The difference, roughly Rs. 11.23 lakh, is your estimated wealth gain purely from compounding. Notice how the growth accelerates in the later years — this is why starting early matters far more than investing a larger amount later.

Rules, Assumptions and Edge Cases

• The calculator assumes a constant rate of return. Real mutual fund returns fluctuate from year to year, so treat the output as a projection, not a guarantee.
• Equity mutual fund returns are not fixed. A figure like 12% is only a long-term assumption; debt funds typically assume lower returns (often around 6-8%). Rate assumptions are volatile — revisit them periodically.
• Most fund houses allow SIPs starting from as little as Rs. 100 or Rs. 500 per month, making them accessible to almost everyone.
• A step-up SIP (increasing your instalment each year, say by 10%) grows the corpus much faster than a flat SIP; a basic calculator using a single P does not capture this.
• The expense ratio and any exit load slightly reduce real returns and are not modelled by the pure formula.

Tax Treatment (as of FY 2025-26)

Taxation depends on the type of fund and how long each instalment is held. Importantly, every SIP instalment has its own holding period — units bought this month reach long-term status separately from units bought next month (first-in, first-out applies on redemption).

• Equity funds: Gains on units held for more than 12 months are Long-Term Capital Gains (LTCG). LTCG above Rs. 1.25 lakh in a financial year is taxed at 12.5% (without indexation). Units held for 12 months or less attract Short-Term Capital Gains (STCG) at 20%.
• Debt funds: For units bought on or after 1 April 2023, gains are added to your income and taxed at your applicable slab rate, with no LTCG concession.
• ELSS (tax-saving) funds: Qualify for deduction under Section 80C (up to Rs. 1.5 lakh a year, available only under the old tax regime) and carry a 3-year lock-in on each instalment.

Common Mistakes and Tips

• Stopping during market falls. This defeats rupee-cost averaging — the dips are exactly when your fixed amount buys more units.
• Assuming unrealistic returns. Modelling 18-20% for equity over the long term usually leads to disappointment; use conservative assumptions.
• Ignoring inflation. Rs. 23 lakh in 10 years buys less than Rs. 23 lakh today; plan goals in inflation-adjusted terms.
• Not linking the SIP to a goal. Decide the target corpus first, then work backwards to the monthly amount.
• Tip: Increase your SIP with every salary hike — a small annual step-up compounds into a large difference over a decade.