A fixed amount invested in a mutual fund at regular intervals, usually monthly.
A SIP buys units of a mutual fund for a fixed amount on a fixed date each month. Because the amount is fixed and the price moves, more units are bought when the NAV is low and fewer when it is high.
Calculators, including AMFI's and the fund houses' own, treat each instalment as invested at the start of the month and compound monthly: the annuity-due convention. The answer is a projection at the return you assume, not a forecast; equity returns are not steady from year to year.
Figures on this page are filled from the same tax and scheme tables the calculators use, for the current financial year. Every term in the glossary.