What it calculates
The compound interest calculator estimates ending balance, interest earned and total contributions from a starting amount, monthly contribution, annual rate and term.
Choose an amount before the secure payment page opens.
Finance
Browser-sideCompound Interest Calculator
Estimate ending balance, interest earned and contributions with monthly compounding visible.
Inputs
Enter a starting balance, monthly contribution, annual growth rate and term. The result runs locally.
Live answer
Result
Calculations run in this browser session. CalcHarbor does not store entered values.
Support
Keep this free result available
Use the result first. Support and promotional areas stay separate from the useful result.
- Useful result first
- No signup required
- Promotions kept separate
Choose an amount before the secure payment page opens.
Guide and interpretation
Formula
It compounds monthly: future value = principal growth plus monthly contribution growth over the selected number of months.
How to interpret it
Compare interest earned with total contributions to see how much of the balance comes from time and reinvested growth.
Common mistakes
Do not treat an expected rate as guaranteed. Small changes in rate or time can change the ending balance sharply.
Limits
The estimate excludes taxes, fees, inflation, market losses and account rules unless you include them in the assumptions.
FAQ
Are values stored?
No. CalcHarbor calculates in the browser and does not store calculator inputs or results.
Can I use this for final financial decisions?
Use the result as a planning signal. Confirm legal, tax, credit and accounting decisions with a qualified professional.