Compound Interest Calculator
See how your money grows when interest compounds — with future value, total interest, and a year-by-year breakdown.
Year-by-year breakdown
| Year | Starting balance | Interest earned | Ending balance |
|---|
The quiet force behind wealth
Compound interest is often called the eighth wonder of the world: you earn interest not just on your original savings but on every dollar of interest already earned. In the early years the effect looks modest; in the later years it does the heavy lifting. Ten thousand dollars at 7% grows to about $20,000 in ten years — but leave it for thirty and it's over $76,000, with most of the gain arriving in the final decade. Time, more than rate, is the secret ingredient.
This free compound interest calculator shows the full picture: your future balance, how much of it is pure interest, and a year-by-year table so you can watch the snowball build. Switch between yearly, half-yearly, quarterly, and monthly compounding to see how frequency nudges the result. Use it to compare savings accounts, model a retirement fund, or simply to feel the power of starting early.
How to use the compound interest calculator
- Enter your starting amount, the annual rate, and how many years you'll let it grow.
- Choose compounding frequency: monthly is typical for savings accounts.
- Read the breakdown: future value up top, the year-by-year table below.
Frequently asked questions
What is compound interest?
Interest earned on both your original principal and on previously earned interest. Growth accelerates over time because each compounding period adds interest to an ever-larger balance.
How often should interest compound?
More frequent compounding grows money slightly faster: monthly beats quarterly, which beats yearly. The difference is small at low rates but meaningful over decades.
What is the formula for compound interest?
Future value = P × (1 + r/n)^(n×t), where P is principal, r is the annual rate as a decimal, n is compounding periods per year, and t is years. This calculator applies it instantly.
Is this financial advice?
No. This tool is for education and illustration only. It doesn't account for taxes, fees, inflation, or investment risk. Talk to a qualified financial advisor before making decisions.