SIP Calculator

A SIP calculator is a compounding tool that projects the future value of a stream of equal (or annually increasing) monthly investments at an assumed rate of return. It answers the two questions every mutual fund investor asks: "How much will my monthly SIP grow to?" and "How much do I need to invest monthly to reach a target amount?"

Unlike a fixed deposit, a SIP's actual return is not guaranteed — it depends on the fund's market performance. The calculator therefore works with an expected annual return, typically 10–14% for equity funds based on long-term historical index returns, 7–9% for hybrid funds and 6–8% for debt funds.

Why use it before investing?

• Set realistic goals — see whether ₹5,000/month actually reaches your target, or whether you need ₹8,000.
• Compare time horizons — the difference between a 10-year and a 20-year SIP is dramatic and counterintuitive.
• Model step-ups — increasing the SIP 10% each year can nearly double the final corpus over 20 years.
• Separate investment from gain — knowing how much of the maturity value is your own money keeps expectations honest.

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

where:
P = monthly SIP amount
i = monthly rate = annual return ÷ 12 ÷ 100
n = total number of monthly instalments

This is the standard future value of an annuity-due formula, used by AMFI, fund houses and every major SIP platform. The final (1 + i) factor exists because SIP instalments are invested at the start of each period, so each instalment earns one extra month of growth.

Step-by-step example

1. Say P = ₹10,000/month, expected return = 12% p.a., tenure = 10 years.
2. Monthly rate i = 12 ÷ 12 ÷ 100 = 0.01 (1% per month).
3. Number of instalments n = 10 × 12 = 120.
4. (1.01)^120 = 3.3004, so ((3.3004 − 1) / 0.01) = 230.04.
5. FV = 10,000 × 230.04 × 1.01 ≈ ₹23,23,391.
6. Total invested = 10,000 × 120 = ₹12,00,000, so wealth gained ≈ ₹11,23,391 — almost as much as you put in.

Step-up SIP formula

With an annual step-up of s%, the SIP amount for year k becomes P × (1 + s/100)^(k−1). The calculator compounds each year's instalments separately and adds them, which is why a step-up SIP cannot be reduced to a single closed-form expression — and why most competing calculators simply omit it.

Read the table horizontally and the lesson is obvious: doubling the tenure far more than doubles the corpus. A ₹10,000 SIP earns about ₹11 lakh of gains in 10 years but roughly ₹76 lakh of gains in 20 years, because the largest compounding happens in the final years.

Goal-based example: ₹1 crore for retirement

Suppose you want ₹1 crore in 20 years and expect 12% annual returns. Working the formula backwards, you need roughly ₹10,000 per month. Start five years later with only 15 years remaining, and the required SIP nearly doubles to about ₹19,800 per month. Delay is the most expensive decision in SIP investing.

1. Enter your monthly investment — the amount you can commit without touching it in a downturn.
2. Set the expected annual return. Use 10–12% for diversified equity funds as a conservative long-term assumption; avoid plugging in a recent bull-market return like 18%.
3. Choose the time period. SIPs need at least 5–7 years for rupee cost averaging to smooth out market cycles.
4. Optionally set an annual step-up matching your expected salary growth (5–10% is typical).
5. Review the maturity value, invested amount and wealth gained, and use the year-by-year chart to see the compounding curve.

Advantages of SIP investing

• Rupee cost averaging — you automatically buy more units when markets fall and fewer when they rise, lowering your average cost per unit.
• Discipline without timing — the market's best days cluster unpredictably; a fixed monthly date removes the temptation to wait.
• Low entry point — most funds accept SIPs from ₹500/month.
• Flexibility — you can pause, increase, or stop a SIP anytime without penalty (unlike an insurance premium or FD).

Limitations of the calculator

• Returns are assumed constant; real equity returns are volatile, and the sequence of returns affects the outcome.
• It does not model exit load, expense ratio changes or capital gains tax on redemption.
• Inflation is not deducted — ₹1 crore in 20 years buys roughly what ₹31 lakh buys today at 6% inflation.
• Past index averages do not guarantee future performance; treat every projection as an estimate, not a promise.

• Stopping the SIP during a market crash — that is precisely when instalments buy the most units.
• Using an aggressive return assumption (15%+ p.a.) and then under-saving toward the goal.
• Ignoring step-ups — keeping the same SIP for 15 years while your income triples wastes your biggest lever.
• Choosing dividend/IDCW plans for long-term goals — growth plans compound the full NAV.
• Comparing a 12% SIP projection with an 7% FD as if both were guaranteed; only one of them is.