Compound Interest Calculator

What is the Compound Interest Calculator?

Compound interest is interest earned not just on your original principal but also on the interest already accumulated. A compound interest calculator shows how your money snowballs over time and quantifies the advantage of compounding over simple interest.

How does it work?

At each compounding period, interest is added to the balance, and the next period’s interest is calculated on this larger amount. The more frequently interest is compounded — yearly, quarterly, monthly or daily — the faster the balance grows for the same nominal rate.

Formula

A = P × (1 + r/n)^(n·t)

• A = final amount (principal + interest)
• P = principal amount
• r = annual interest rate (as a decimal)
• n = compounding periods per year
• t = time in years

Example calculation

Benefits

• ✓Demonstrates the long-term power of reinvested returns.
• ✓Lets you compare different compounding frequencies easily.
• ✓Highlights why starting early matters so much for wealth.

Limitations

• !Assumes a constant rate and no withdrawals.
• !Ignores taxes and inflation that erode real returns.
• !Real-world investments rarely compound at a perfectly fixed rate.

Conclusion

Compounding is often called the eighth wonder of the world for good reason — time is its most powerful ingredient. Start early, reinvest your returns, and let frequency and patience do the heavy lifting.