Interest Rates

What Are Interest Rates?

Interest rates are the cost of borrowing money or the return earned on savings, expressed as a percentage of the principal amount.

When you borrow money through a loan, mortgage, or credit card, the interest rate determines how much extra you pay back on top of the original amount. When you deposit money in a savings account or invest in bonds, the interest rate determines how much your money grows over time.

Types of Interest Rates

There are two main types of interest rates that affect everyday financial decisions:

Simple interest

Simple interest is calculated only on the principal amount, meaning the initial sum of money. It does not account for any interest that may have accumulated over time. For example, if you lend $1,000 at a 5% simple interest rate for one year, you earn $50 in interest.

Compound interest

Compound interest is calculated not just on the initial amount but also on the accumulated interest from previous periods. In practical terms, you end up paying or earning interest on the interest. This means the total amount grows faster over time compared with simple interest, particularly when compounding occurs frequently.

Why Do Interest Rates Matter?

When a central bank raises interest rates, borrowing becomes more expensive, which can slow down spending and help control inflation. When rates are lowered, borrowing becomes cheaper, which may encourage spending and investment during periods of economic weakness or recession.

For individuals, the interest rate determines the cost of a mortgage or car loan and the return on a savings account. A higher rate means higher borrowing costs but also higher returns on savings. For businesses, interest rates affect the cost of financing operations and expansions, which can influence hiring and investment decisions.

Interest rates also interact with inflation. When inflation is high, the real return on savings may be lower than the nominal interest rate suggests, because the purchasing power of money declines over time. Central banks monitor this relationship closely and may adjust rates to keep inflation near their target, typically around 2% in many advanced economies.