What's the difference between simple and compound interest?

Simple interest is calculated only on the principal, while compound interest is calculated on the principal plus accumulated interest.

How often should interest compound?

More frequent compounding (daily vs annually) results in slightly more interest earned, though the difference diminishes at higher frequencies.

Divide 72 by the annual interest rate to estimate how many years it takes to double your money. At 6%, it takes about 12 years.

Compound Interest Formula on CalcAll — free educational content with detailed examples.

What's the difference between simple and compound interest?: Simple interest is calculated only on the principal, while compound interest is calculated on the principal plus accumulated interest.
How often should interest compound?: More frequent compounding (daily vs annually) results in slightly more interest earned, though the difference diminishes at higher frequencies.
What is the Rule of 72?: Divide 72 by the annual interest rate to estimate how many years it takes to double your money. At 6%, it takes about 12 years.