A Systematic Investment Plan is a method of investing an amount into a mutual fund at regular intervals. It is not a separate asset and does not guarantee returns.
Units and NAV
Each contribution buys units at the NAV applicable under the scheme's transaction rules. A fixed contribution buys more units at a lower NAV and fewer at a higher NAV. The final result still depends on the complete price path and the value when units are sold; periodic purchasing does not guarantee a profit or a lower average cost than another timing method.
Measuring a SIP
Because contributions occur on different dates, a money-weighted measure such as XIRR can describe the annualised rate that reconciles those dated cash flows with an ending value. XIRR is a measurement of what happened, not a forecast of what will happen.
Planning with a SIP calculator
The calculator uses the monthly payment-timing convention disclosed on the tool. Enter a monthly contribution, horizon and return assumption to produce an illustration. For goal planning, compare multiple assumptions instead of treating a fixed percentage as an expected market return.
A step-up SIP increases the contribution according to the schedule entered by the user. It can produce a larger modeled corpus because more money is contributed; that does not establish a superior product or future return.
Before starting or changing a SIP, review the underlying scheme, risk, costs, tax treatment and exit terms. The investment outcome belongs to the fund and market path, not to the payment instruction itself.