Compound Interest Calculator
Free compound interest calculator: see future value with yearly, quarterly, monthly or daily compounding and optional yearly contributions.
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Runs in your browser. Nothing you enter is uploaded.
How to use the Compound Interest Calculator
- Enter the starting amount.
- Enter the yearly interest rate and years.
- Choose how often interest compounds.
- Optionally add a yearly contribution and read the growth table.
What is compound interest?
Compound interest is interest earned on both your original money and on interest already added. Over long periods this snowball effect makes growth far larger than simple interest.
A = P × (1 + r ÷ n)^(n × t)
P = principal, r = annual rate, n = compounding periods per year, t = years
Worked example
100,000 at 8% for 10 years: yearly compounding gives 215,892. Monthly compounding gives 221,964. More frequent compounding helps, but the rate and time matter much more.
Simple vs compound interest
Simple interest on 100,000 at 8% for 10 years is 80,000, ending at 180,000. Compounding earns 115,892 in the same time.
The rule of 72
Divide 72 by the annual rate to estimate how many years it takes money to double. At 8% that is about 9 years.
Frequently asked questions
What is the compound interest formula?
A = P(1 + r/n)^(nt), where n is how many times interest is added per year.
Does compounding more often earn more?
Slightly. Going from yearly to monthly compounding adds a little, but a higher rate or more years adds far more.
Can I add money each year?
Yes, use the yearly addition box. Contributions are added at the end of each year.
Is compound interest the same as CAGR?
They are related. CAGR is the equivalent yearly compounded growth rate between a start and end value.