Investment & Interest Calculators

Choosing the right investment calculator starts with understanding your financial goal. If you want to see how a lump sum or regular contributions grow over time, the compound interest calculator is your best starting point. It works for savings accounts, CDs, bonds, and general investment projections.

When evaluating investments, consider both the rate of return and the compounding frequency. Money that compounds daily grows slightly faster than money compounding annually at the same rate. Our calculators let you compare these scenarios side by side to understand the real difference.

For long-term planning, factor in inflation. A nominal return of 8% with 3% inflation means your real purchasing power grows at roughly 5% per year. Use our tools to model different scenarios and build a realistic picture of your financial future.

Compound interest is often called the eighth wonder of the world, and for good reason. Unlike simple interest, which is calculated only on the original principal, compound interest earns returns on both the principal and the accumulated interest from previous periods. This creates an exponential growth curve that accelerates over time.

The formula for compound interest is A = P(1 + r/n)^(nt), where A is the final amount, P is the principal, r is the annual interest rate, n is the number of times interest compounds per year, and t is the number of years. While the math may seem complex, the concept is straightforward: your money earns money, and then that earned money earns even more money.

Time is the most powerful factor in compound growth. Starting to invest early, even with smaller amounts, typically outperforms investing larger amounts later. For example, investing $200 per month starting at age 25 with an 8% annual return yields approximately $702,000 by age 65. Waiting until age 35 to start the same investment results in only about $298,000, less than half, despite investing for just ten fewer years.

The Rule of 72 provides a quick way to estimate how long it takes for an investment to double. Simply divide 72 by the annual rate of return. At 8% returns, your money doubles approximately every 9 years. At 12%, it doubles every 6 years. This simple mental math can help you quickly evaluate investment opportunities.