What a SIP is
A systematic investment plan, or SIP, means putting a fixed amount into an investment on a regular schedule, usually monthly. The idea is discipline: you invest through ups and downs rather than trying to guess the right moment. When prices are low your money buys more units, and when they are high it buys fewer.
The calculator treats a SIP as a monthly saving that grows at a steady annual rate. It works just as well for a recurring deposit or a plain savings plan.
SIPs became popular because they remove decisions. The amount leaves your account on a set date, so saving happens first and spending adjusts around it. Many people also raise the amount a little each year when their income rises, which this calculator can mimic if you rerun it with a bigger figure.
Future value with a worked example
Invest 5,000 a month for 10 years with an assumed return of 12 percent a year. The monthly rate is 1 percent and there are 120 payments. The result is roughly 1.15 million. You put in 600,000 yourself, and about 550,000 is growth.
Extend the same plan to 20 years and the balance reaches about 4.95 million on 1.2 million invested. Doubling the time more than quadruples the outcome. That is why starting early matters more than the size of the monthly amount.
The calculator also shows the invested total beside the future value, so you can see the gain separately. This split is a useful sanity check: if the gain looks too large for the years involved, your return assumption is probably too high.
Working backwards from a goal
Goal mode flips the question. Say you want 1,000,000 in 10 years and expect 12 percent. The calculator estimates you need about 4,350 a month. If that is too high for your budget, you have three levers: save for more years, accept a smaller goal, or find a higher return, which usually means taking more risk.
Use it for concrete plans: a down payment, a wedding, school fees or an emergency fund. Write the date next to the number, since a goal with a deadline is easier to stick to.
If the monthly figure is out of reach, try lengthening the period by two or three years before changing the goal. Because compounding builds on itself, those extra years usually cut the monthly amount by more than you would guess.
Be careful with the return assumption
Nobody knows what return an investment will deliver. Savings accounts pay low, steady rates, while stock-based funds swing widely and may lose money in some years. Run the calculation with a conservative rate and an optimistic one, and plan around the lower number.
Inflation reduces the value of the future sum, and fees reduce the return. This is an estimate to help you plan, not a prediction, and not financial advice.