About the Compound Interest Calculator
See how money grows with compound interest: set a starting amount, interest rate, time period, compounding frequency and optional monthly contributions. Results show final balance, total contributions and total interest earned with a year-by-year table.
Visualizing compounding is the single best motivation for long-term saving — small regular contributions become surprisingly large.
How to use the Compound Interest Calculator
- Enter initial amount, annual rate and years.
- Choose compounding frequency and optional monthly deposit.
- Read the final value and year-by-year growth table.
Common uses
Projecting savings account growth
Planning retirement contributions
Comparing investment scenarios
Frequently asked questions
What is compound interest?
Interest earned on both your principal and previously earned interest — growth accelerates over time.
How much difference does frequency make?
More frequent compounding helps slightly; the bigger factors by far are rate, time and regular contributions.
What formula is used?
A = P(1 + r/n)^(nt) for the principal, plus the future value of the contribution series.
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