Savings
Compound Interest
How to use this compound interest calculator
- Enter the requested values in the calculator.
- Review the result immediately below the fields.
- Use the explanation and example below to check how the result was obtained.
Method and formula
Interest is applied monthly using the annual rate divided by twelve. The monthly contribution is added after that month's growth, and the chart separates contributions from estimated growth.
Worked example
At 6% annually, $10,000 with $200 added monthly grows through both new contributions and interest earned on earlier balances.
What the result does not include
Actual investment returns fluctuate and may be negative. Taxes, inflation, account fees, contribution timing, and changing rates are not included.
Frequently asked questions
Are the calculations saved?
No. The calculation runs in your browser. This site does not receive or store the numbers and dates entered into a calculator.
Why can another calculator show a slightly different result?
Results can differ because of rounding, input units, timing assumptions, or extra fees and variables. Keep full precision until the final step and compare the assumptions used by each source.
Can I use this result for an official decision?
Use it as an educational estimate and a way to check your own arithmetic. For medical, financial, academic, or legal decisions, confirm the result with the relevant professional or institution.