What does starting late cost you?

Why a short delay costs so much

It feels like waiting six months or a year to start a SIP should cost you roughly six months or a year of contributions. It doesn't — it costs far more, and the reason is where the missing months sit in your timeline. The instalments you skip by starting late aren't the small, recent ones near the end of your horizon. They're the earliest ones — the rupees that would have had the most years to compound. An instalment invested in year one of a 20-year plan compounds for two decades; the same rupee invested in the final year barely compounds at all. Delaying lops off the front of your plan, which is precisely the most valuable part.

The asymmetry in plain numbers

At a 12% assumed return, money roughly doubles every six years. So a contribution made today is worth about twice as much at the finish line as the identical contribution made six years from now, and about four times as much as one made twelve years from now. That multiplier is why a delay near the start of a long horizon is so expensive: every month you postpone, you forfeit a month that sits at the high-multiplier end of the curve and replace it (at best) with a month at the low-multiplier end. The calculator above makes this concrete — try a 20-year horizon and watch how a one-year delay removes far more than one year's worth of contributions from the final figure.

What this does and doesn't mean

The honest takeaway isn't “invest at any cost, immediately.” If starting now means borrowing, skipping an emergency fund, or stretching beyond what you can sustain, that's a worse trade than waiting a few months to start on solid footing — a SIP you have to stop early can cost more than one you start a little late. The point is narrower and more useful: among the things you control, starting sooner is usually the highest-leverage one. Increasing the amount later, or chasing a higher return, rarely recovers what early time would have earned for free. The figures here assume a constant return for clarity; real markets are volatile, and no return is guaranteed.