SIP Calculator Guide: Formula, Examples & How to Plan Goals (2026)

Quick Answer: How Is SIP Maturity Calculated?

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

• P = amount invested each month
• i = monthly rate of return = annual rate ÷ 12 ÷ 100
• n = number of monthly instalments

Example: investing 5,000 a month for 10 years at an assumed 12% a year gives roughly 11.6 lakh, against a total investment of 6 lakh.

What Is a SIP?

A Systematic Investment Plan is a way of investing a fixed amount at fixed intervals, most commonly every month, into a mutual fund or a similar market-linked product. You give your bank a standing instruction, and the amount is debited automatically on a chosen date and used to buy units of the fund at that day’s price.

A SIP is not a product by itself. It is a method of investing. The underlying investment could be an equity fund, a debt fund, a hybrid fund or an index fund. The risk and likely return depend on that underlying fund, not on the SIP method.

Why People Like SIPs

• Discipline: automatic debits make saving a habit instead of a decision you must repeat every month.
• Affordability: you can start with a modest amount.
• No need to time the market: your money enters at many different price levels.
• Power of compounding: returns earn further returns over long periods, as explained in our guide to compound interest.
• Flexibility: most plans let you pause, increase or stop the SIP, subject to the fund’s rules.

How a SIP Works

Suppose you start a SIP of 1,000 a month. In month one, the fund’s price (called NAV) is 10, so you receive 100 units. In month two, the NAV falls to 8, so the same 1,000 buys 125 units. In month three, the NAV rises to 12, so you get about 83.33 units. Each instalment buys whatever number of units the price allows.

Over time, you accumulate units. The value of your investment at any moment is the number of units multiplied by the latest NAV. When you eventually redeem, you receive that value, subject to any exit load and taxes.

Two things drive the end result: how much you invest and for how long, and what the underlying investment earns. The first is under your control. The second is not, which is why calculators use an assumed rate of return and why you should treat their output as an estimate.

The SIP Formula Explained

Each monthly instalment grows for a different length of time. The first one grows for all n months, and the last one for just one month. Adding all these growing instalments together gives the future value of an annuity:

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

Preparing the Inputs

• Monthly rate i: divide the annual rate by 12 and then by 100. For 12%, i = 0.01. For 8%, i ≈ 0.006667.
• Number of months n: multiply years by 12. Ten years is 120 months.

Why the Extra (1 + i)?

The final multiplication assumes each instalment is invested at the start of the month. Many SIP calculators use this convention. If you assume investments happen at the end of the month, drop the last (1 + i). The difference is small: for 5,000 a month at 12% over 10 years, the start-of-month result is about 11.62 lakh, while the end-of-month result is about 11.50 lakh. Always check which convention a calculator uses when comparing results.

The (1 + i)ⁿ term is a power, so if exponents are unfamiliar, read our guide on square roots and exponents first.

Step-by-Step Example

Example 1: 5,000 a Month for 10 Years at 12%

1. P = 5,000.
2. i = 12 ÷ 12 ÷ 100 = 0.01.
3. n = 10 × 12 = 120.
4. (1.01)¹²⁰ ≈ 3.3004.
5. ((3.3004 − 1) ÷ 0.01) = 230.04.
6. Multiply by (1 + i): 230.04 × 1.01 ≈ 232.34.
7. FV = 5,000 × 232.34 ≈ 11,61,700 (about 11.62 lakh).

Total invested = 5,000 × 120 = 6,00,000. Estimated gain = about 5.62 lakh. In this illustration, more than 48% of the final value comes from growth rather than from your own contributions.

Example 2: 2,000 a Month for 5 Years at 12%

n = 60, and (1.01)⁶⁰ ≈ 1.8167. ((1.8167 − 1) ÷ 0.01) × 1.01 ≈ 82.49. FV = 2,000 × 82.49 ≈ 1,64,970 (about 1.65 lakh) on an investment of 1,20,000.

Example 3: A Lower Return of 8%

5,000 a month for 10 years at 8%: i ≈ 0.006667, (1 + i)¹²⁰ ≈ 2.2196. ((2.2196 − 1) ÷ 0.006667) × 1.006667 ≈ 184.17. FV ≈ 5,000 × 184.17 ≈ 9,20,800 (about 9.21 lakh).

Effect of Time

Time is the biggest lever in a SIP. The table below shows 5,000 a month at an assumed 12% a year for different durations.

Notice the pattern. Doubling the time from 10 to 20 years does not merely double the result; it more than quadruples it. Growth is back-loaded, so the later years add much more than the early years. This is the compounding effect at work.

Effect of the Return Rate

The assumed return also matters, but over realistic ranges, it matters less than the duration. Here is 5,000 a month for 10 years at three different assumed rates.

Real markets do not deliver a smooth fixed rate each year. A fund could return 25% in one year and lose 10% in the next. A calculator smooths this into a single average, so your actual result could be higher or lower. It is wise to run your plan with a conservative rate as well as an optimistic one.

The Cost of Waiting

Starting late is expensive. Take 5,000 a month at an assumed 12% a year:

• Invested for 30 years: about 1.76 crore.
• Invested for 20 years: about 49.96 lakh.

A ten-year delay reduces the end result by about 1.26 crore, even though the difference in money invested is only 6 lakh. The first decade’s contributions have the longest time to compound, so they end up contributing the most. This is the strongest argument for starting early, even with a small amount, and increasing it later.

Rupee Cost Averaging

Rupee cost averaging is the effect of investing a fixed amount at regular intervals while prices move up and down. When prices are low, your fixed amount buys more units. When prices are high, it buys fewer. Over time, your average cost per unit tends to be lower than the simple average of the prices.

A Worked Example

You invest 1,000 each month for four months, when the NAV is 10, 8, 12 and 10.

• Units bought: 100 + 125 + 83.33 + 100 = 408.33 units.
• Total invested: 4,000.
• Your average cost per unit: 4,000 ÷ 408.33 ≈ 9.80.
• The simple average of the four NAVs: (10 + 8 + 12 + 10) ÷ 4 = 10.

You paid a slightly lower average price than the average NAV, because the dip to 8 bought extra units. Rupee cost averaging does not guarantee profit or protect against loss in a falling market, but it reduces the stress of trying to pick the “right” day to invest.

Planning a Goal with SIP

You can also run the formula backwards to find the monthly amount needed to reach a target. Rearranging gives:

P = Target ÷ { [((1 + i)ⁿ − 1) ÷ i] × (1 + i) }

Example 1: 1 Crore in 15 Years

At an assumed 12% a year, i = 0.01 and n = 180. The multiplier is [((1.01)¹⁸⁰ − 1) ÷ 0.01] × 1.01 ≈ 504.58. P = 1,00,00,000 ÷ 504.58 ≈ 19,800 per month.

Example 2: 50 Lakh in 10 Years

The multiplier for 120 months at 12% is about 232.34. P = 50,00,000 ÷ 232.34 ≈ 21,520 per month.

Steps for Goal-Based Planning

1. Define the goal and the date. For example, a child’s college fund needed in 12 years.
2. Adjust the target for inflation. A cost of 20 lakh today may be much more in the future. Our guide on how inflation is calculated shows how.
3. Pick a realistic return assumption. Use a lower rate for shorter goals and safer investments.
4. Calculate the monthly amount with the formula or a calculator.
5. Review once a year. Adjust if the goal, your income or the markets change.

For goals within three to five years, many planners suggest lower-risk options, because a market fall just before you need the money could hurt. For long-term goals like retirement, higher-growth options may be considered, subject to your own risk tolerance.

Step-Up SIP

A step-up (or top-up) SIP increases your monthly investment at set intervals, typically once a year, by a fixed percentage or amount. This lets your investment grow along with your income.

Suppose you start with 5,000 a month and raise it by 10% each year. In year two you invest 5,500, in year three 6,050, and so on. Over 10 years, your total contribution becomes much larger than with a flat 5,000, and the final corpus is considerably bigger. Even a small step-up of 5% a year makes a visible difference over a long period.

Step-up is also a useful way to deal with inflation: if your salary rises each year, increasing your SIP by a similar percentage keeps your savings rate stable. For understanding yearly growth in percentage terms, see our guide on percentage increase and decrease.

SIP vs Lump Sum vs Recurring Deposit

There is no single best option. A lump sum can do better if you invest right before a long rising market, and worse if you invest just before a fall. A SIP spreads that risk. An RD offers certainty but may offer lower growth. To compare a fixed-rate deposit with a market investment properly, read our guides on simple interest and how to calculate ROI.

Inflation, Costs and Real Returns

A SIP calculator shows a nominal number. To judge how much your future money will actually buy, subtract the effect of inflation. If your investment grows at 12% a year and inflation is 6%, your real growth is about (1.12 ÷ 1.06) − 1 ≈ 5.7% per year. An end value of 11.62 lakh after 10 years would have the purchasing power of roughly 6.5 lakh in today’s money at 6% inflation (11.62 lakh ÷ 1.06¹⁰ ≈ 6.49 lakh).

Costs also reduce your return:

• Expense ratio: the annual fee charged by the fund, deducted from returns. Even a 1% difference matters over decades.
• Exit load: a fee some funds charge if you redeem within a set period.
• Taxes: gains may be taxable depending on the fund type and holding period. Tax rules change, so check the current rules or consult a tax professional.

Risks and Things to Check

• Market risk: the value of your units can fall, particularly over short periods.
• No guaranteed return: a SIP is a method, not a promise.
• Fund selection risk: the choice of fund, its objective and its costs strongly affect results.
• Behavioural risk: stopping your SIP during a market fall can lock in losses and miss the recovery.
• Liquidity: some products have lock-in periods.

Before you start, check the fund’s objective, past performance over several market cycles (not just one year), expense ratio, the fund house’s track record and whether the risk level suits you. Match the investment horizon to the goal. Please remember that this article is educational, not personalised financial advice, and you should consider speaking with a registered adviser.

Common Mistakes

1. Stopping a SIP when markets fall. This is often when units are cheapest.
2. Expecting guaranteed returns. Calculators use assumed rates, not promises.
3. Starting too late. The cost of delay is much larger than most people expect.
4. Using an unrealistic return assumption. Planning with an overly optimistic rate leads to shortfalls.
5. Ignoring inflation. A target that sounds large today may be small in the future.
6. Chasing last year’s top fund. Past returns do not guarantee future results.
7. Investing money needed in the short term. Market-linked SIPs suit longer horizons.
8. Never increasing the amount. As income grows, a step-up helps keep pace.
9. Skipping an emergency fund. Without one, you may be forced to withdraw at a bad time.

Practice Questions

1. What is the monthly rate for an assumed annual return of 12%?
2. How much is invested in total if you invest 3,000 a month for 8 years?
3. Roughly how much monthly SIP is needed to reach 50 lakh in 10 years at an assumed 12%?
4. You invest 1,000 when the NAV is 10 and 1,000 when the NAV is 8. What is your average cost per unit?
5. Estimate the maturity value of 2,000 a month for 5 years at an assumed 12%.
6. If the assumed return is 12% and inflation is 6%, what is the approximate real return?

Answers

1. 12 ÷ 12 ÷ 100 = 0.01 (1% per month).
2. 3,000 × 96 months = 2,88,000.
3. About 21,520 per month.
4. Units = 100 + 125 = 225. Average cost = 2,000 ÷ 225 ≈ 8.89.
5. About 1.65 lakh.
6. (1.12 ÷ 1.06) − 1 ≈ 5.7%.

Frequently Asked Questions

What is a SIP?

A Systematic Investment Plan invests a fixed amount at regular intervals, usually monthly, into a mutual fund or similar investment.

How is SIP return calculated?

A common formula is FV = P × [((1 + i)ⁿ − 1) ÷ i] × (1 + i), with P as the monthly amount, i as the monthly return and n as the number of months.

Are SIP returns guaranteed?

No. SIPs in market-linked funds carry risk, and calculators only show illustrations based on an assumed return.

What is rupee cost averaging?

It means buying more units when prices are low and fewer when prices are high, which can bring down your average cost per unit over time.

What is a step-up SIP?

A step-up SIP raises your monthly amount by a fixed percentage or amount each year, in line with your income growth.

How long should I invest in a SIP?

Longer is generally better. Many planners suggest at least five years for equity-oriented funds so that short-term swings have time to even out, but this depends on your goal and risk comfort.

Can I stop a SIP anytime?

In most cases, yes. You can pause or stop it, subject to the fund’s rules and any exit load on units you redeem.

Conclusion

A SIP rewards consistency. By investing a fixed amount regularly, you build discipline, spread your entry points and give compounding the time it needs. Use the formula to estimate outcomes, work backwards from your goals, consider a yearly step-up, and be realistic about returns, costs and inflation. Above all, start early and stay invested through the ups and downs, while remembering that market investments carry risk.

Try different amounts, durations and return assumptions with our free SIP calculator, and keep learning with these related guides:

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• Compound Interest Explained
• Inflation Calculator Explained
• How to Calculate ROI
• How EMI Is Calculated
• Simple Interest Formula
• Percentage Increase and Decrease