Compound interest

Why 100 becomes 1,497

  • Chapter 1 / 168
  • 3 min
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Marie and Paul. Same job, same pay, same life. At sixty, Marie has thirty thousand euros more than Paul, even though she put in two and a half times less.

She didn't earn more. She didn't spend less. She just started earlier.

She didn't earn more. She didn't spend less. She just started earlier.

To get why, you need to look at something your brain almost always underestimates.

To get why, you need to look at something your brain almost always underestimates.

Say you put away a hundred euros. Just once. And you don't touch it for forty years.

It earns you seven percent a year. That's roughly what stocks have made on average over the last century. Nothing special.

After forty years, how much do you have? Take three seconds.

Most people say three hundred and eighty euros: a hundred to start, plus seven a year for forty years.

The real answer is one thousand four hundred and ninety-seven.

Almost four times more than you'd guess. And all you did was wait.

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Here's why. In year one, you make seven euros. Nothing surprising so far.

Here's why. In year one, you make seven euros. Nothing surprising so far.

In year two, you don't make seven percent of a hundred euros. You make it on a hundred and seven.

In year two, you don't make seven percent of a hundred euros. You make it on a hundred and seven.

Then on a hundred and fourteen. Then a hundred and twenty-two. Your interest earns interest. That's what we call compound interest.

Then on a hundred and fourteen. Then a hundred and twenty-two. Your interest earns interest. That's what we call compound interest.

That's it. No trick, no magic investment. Just this little loop, forty times over.

That's it. No trick, no magic investment. Just this little loop, forty times over.

Look at the shape it makes.

For twenty years, almost nothing happens. The curve stays flat, hugging the bottom line.

And that's where most people give up: they see nothing coming, so they pull everything out.

Then it takes off. Half of all the gains come in the last ten years.

Back to Marie and Paul. Marie starts at twenty-five. She puts two hundred euros aside every month.

Back to Marie and Paul. Marie starts at twenty-five. She puts two hundred euros aside every month.

At thirty-five, she stops. Ten years of saving, then nothing. She just leaves it alone.

At thirty-five, she stops. Ten years of saving, then nothing. She just leaves it alone.

Paul starts at thirty-five, the day Marie stops. He puts in two hundred euros a month until he's sixty.

Paul starts at thirty-five, the day Marie stops. He puts in two hundred euros a month until he's sixty.

Paul put in sixty thousand euros. Marie, twenty-four thousand. Two and a half times less.

Paul put in sixty thousand euros. Marie, twenty-four thousand. Two and a half times less.

At sixty, Marie has one hundred and eighty-six thousand euros. Paul has one hundred and fifty-seven thousand.

The one who put in less ends up with more. Her money simply got a ten-year head start.

The one who put in less ends up with more. Her money simply got a ten-year head start.

Time matters more than the amount. If you remember just one thing, make it this one.

The best time to start was ten years ago. The second best time is today.

The best time to start was ten years ago. The second best time is today.

Compound interest

In the app, this chapter is animated and narrated, card by card.

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