In one line: Compound interest is growth on your growth: over time your money can snowball because past gains start earning too.
Compound interest is the single idea that makes long-term investing powerful. Once you see it, the value of starting early clicks into place.
What does growth on top of growth mean?
Imagine a small snowball rolling downhill. It picks up snow, gets bigger, and because it is bigger it picks up even more. Compounding works the same way: any growth your money earns can itself go on to earn more. Early on it feels slow; given enough time, it can build momentum.
Why does time matter more than amount?
Because the snowball feeds on itself, the length of the hill — your time horizon — often matters more than how big the snowball starts. Starting earlier with a little can, over many years, do more than starting later with a lot. There are no guarantees, but time is the ingredient compounding needs most.
Does compounding cut both ways?
The same force works against you when it comes to costs and inflation: high fees and rising prices also compound over time, quietly eating into growth. That is why long-term thinking tends to favour keeping costs low and staying patient.
Key takeaways
- Compounding means your gains start earning gains of their own.
- The effect builds slowly, then accelerates — time is the key ingredient.
- Starting earlier often matters more than starting bigger.
- Costs and inflation compound too, so they are worth keeping low and in mind.