Compound Interest and Time
How money can earn money on its own, and why starting early is the most powerful move you have.
What compound interest is
Compound interest means you earn interest not only on the money you put in, but also on the interest it has already earned. Over time, the growth feeds on itself and speeds up.
Put 100 dollars where it earns 5 percent a year. After one year you have 105 dollars. The next year, 5 percent is figured on 105, not 100, so you earn a little more. Each year the base is bigger, so each year adds more than the last.
Why starting early matters
The longer money compounds, the more the later years do the heavy lifting. Time, not just the amount, is what makes the total grow large.
- A person who starts setting money aside at 20 gives it far more years to compound than one who starts at 35.
- Because the early dollars compound the longest, they often grow more than dollars added much later.
- This is the core idea behind starting early: time does work that bigger deposits later cannot fully catch up to.
It works both ways
Compounding is powerful in your favor when you are saving, and powerful against you when you owe. The same math that grows savings also grows an unpaid debt, since interest piles onto interest.
That is why a high-rate balance left alone can balloon, while steady savings left alone can quietly build. The direction depends on which side of the interest you are on.
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