Compound Interest Guide
Compound Interest vs Simple Interest
Compare compound interest and simple interest, including when each one matters and why compound growth can be stronger over time.
In this guide
The main difference Why compound interest grows faster When simple interest still appearsThe main difference
Simple interest is calculated only on the original principal. Compound interest is calculated on the principal plus previously earned interest.
If you earn simple interest on $1,000 at 5%, you earn $50 each year. If you earn compound interest, the second year starts from $1,050, so the next 5% is slightly larger.
Why compound interest grows faster
Compound interest creates a feedback loop. Growth is added to the balance, and that larger balance can create more growth in the next period. The difference may be small at first, but it can become meaningful over long periods.
This is one reason long-term savings and investment education often emphasizes starting early.
When simple interest still appears
Simple interest can still appear in some loans, short-term calculations, or educational examples. It is easier to calculate, but it does not capture the snowball effect of reinvested earnings.
For long-term savings and investing, compound interest is usually the more relevant model.