Grow

Grow — a compound interest, SIP and goal calculator that shows how contributions and interest build your wealth over time.

Compound growth is the one piece of financial mathematics worth internalising, because intuition about it is reliably wrong — people extrapolate linearly and are consistently surprised by the back end of the curve, where most of the total is created.

The rule of 72 is the quick version: divide 72 by the annual return to get the doubling time. Regular contributions change the shape again, since each one compounds for a different length of time, which is why starting earlier beats contributing more later by a margin that looks implausible until you see it laid out.