What Is Compound Interest? Why It Matters
Learn what compound interest is, how it works, see real examples, and understand why starting early makes a massive difference in wealth building.
Guide overview
Einstein allegedly called compound interest the "eighth wonder of the world." True or not, the math behind it is undeniably powerful.
Learn what compound interest is, how it works, see real examples, and understand why starting early makes a massive difference in wealth building.
Key points from the source guide
The source guide contrasts simple interest with compound interest and its interest-on-interest effect.
It uses a start-early investing example to show how time changes the ending balance.
It introduces the Rule of 72 as a quick way to estimate doubling time.
Try the related Toolars calculators
This migrated guide links to these Toolars tools: compound-interest, apy-calculator.
Tools mentioned in this article
Frequently asked questions
- How is compound interest different from simple interest?
- Simple interest is calculated only on the principal amount. Compound interest is calculated on the principal plus accumulated interest. Over time, compound interest grows exponentially while simple interest grows linearly.
- What is the best compound frequency?
- More frequent compounding yields slightly higher returns. However, the difference between monthly and daily compounding is usually small. Focus more on the interest rate than the frequency.