Compound Interest Calculator

Compound interest is the interest calculated on the initial principal and also on the accumulated interest of previous periods. It’s often described as “interest on interest.” Unlike simple interest, which is calculated only on the principal amount, compound interest allows your investment to grow at an accelerated rate over time. The more frequently interest is compounded, the faster your investment grows.

The frequency of compounding can significantly impact your investment growth. More frequent compounding (daily or monthly) will yield higher returns than less frequent compounding (annually). However, the actual compounding frequency depends on your investment vehicle. Savings accounts might compound daily, while some bonds compound semi-annually. Our calculator allows you to see how different compounding frequencies affect your final balance.

Inflation reduces the purchasing power of your money over time. While your investment might grow in nominal terms, inflation can erode its real value. Our calculator helps you understand the real growth of your investment by adjusting for inflation. For example, a 7% return with 2.5% inflation means your real return is approximately 4.5%. This gives you a more accurate picture of your investment’s growth in terms of purchasing power.

Taxes can significantly reduce your investment returns, especially in taxable accounts. Different types of investments are taxed differently. For example, long-term capital gains are typically taxed at a lower rate than ordinary income. Our calculator allows you to input your expected tax rate to see how taxes will affect your final balance. Tax-advantaged accounts like 401(k)s or IRAs can help minimize the tax impact on your investments.

The rule of 72 is a simple way to estimate how long it will take for an investment to double at a fixed annual rate of return. Divide 72 by your annual interest rate to get the approximate number of years it will take for your investment to double. For example, at 8% interest, your investment will double in approximately 9 years (72 ÷ 8 = 9). This rule provides a quick estimate but is less accurate for higher interest rates or longer time periods.