Compounding is a feature, not a bug

The boring math that turns small, regular contributions into large, eventually-noticeable sums.

1 min read

The most common question I get from new investors is some version of: “is it really worth starting with so little?” The honest answer is that the early years feel like nothing is happening. That’s not a flaw in the strategy. It’s the strategy.

A small example

Suppose you put $200 a month into a low-cost index fund returning 7% annually after inflation. After year one you have about $2,500. Underwhelming. After year ten you have about $34,500 — still feels modest. After year thirty you have about $244,000, of which only $72,000 was your contributions.

The interesting line in that table isn’t any individual year. It’s the slope. The slope changes.

Why the early years feel slow

In the first decade the dominant input is your savings rate, not the return. A 1% better fund barely matters; a 10% higher contribution matters a lot. This is why personal finance writing tends to focus on spending and earning rather than stock picking — the lever that actually moves the early line is the one you control directly.

What changes around year fifteen

Somewhere between years twelve and twenty, the math flips. Returns start producing more dollars per year than your contributions do. You stop being a saver and start being an owner. The portfolio is now working harder than you are.

The trick is making it that far without flinching when markets drop 30%. Which they will. Repeatedly.

The unglamorous prescription

Automate the contribution. Pick a sensible asset allocation. Don’t look at the balance during sell-offs. Re-read this post in 2046.