Compound Interest Calculator
See how a lump sum grows over time. A = P(1 + r/n)^(nt)
What is compound interest?
Compound interest is interest earned on both the principal and the interest already earned. Example: $1,000 at 5%, compounded monthly for 10 years, grows to $1,647.01.
How to use it
Enter the principal, annual rate, how many times interest is compounded per year, and the years, then tap Calculate.
Formula
A = P(1 + r/n)^(nt), where P is the principal, r is the annual rate, n is the number of compounding periods per year, and t is the years. For $1,000 at 5% compounded monthly for 10 years, A = 1000 × (1 + 0.05/12)^(12 × 10) = $1,647.01.
Frequently Asked Questions
What is $1,000 worth at 5% for 10 years with monthly compounding? $1,647.01, with $647.01 of interest.
What is the difference from simple interest? Simple interest pays interest only on the principal, so it grows more slowly.
Does compounding more often help? Yes, more compounding periods per year give a slightly higher future value.