Compound Interest Calculator

Project growth with compounding & optional contributions

Input OFF

Input Validation
Checks that principal, rate, and term are provided and within valid ranges.

Rate OFF

Interest Rate
Annual rate validated between 0.001% and 50%. Typical savings 2–7%; stocks ~10%.

Term OFF

Investment Term
Duration in years validated between 0.5 and 50 years. Longer terms show more compounding effect.

Output OFF

Calculation Output
Final balance, total interest earned, total contributions, and effective APY.

Parameters

Principal Amount ($)

Annual Interest Rate (%)

Compounding Frequency

Time Period (Years)

Monthly Contribution ($)

Results

Final Balance

$0.00

Total Interest Earned

$0.00

Total Contributions

$0.00

Effective APY

0.00%

Growth Multiple

1.00×

Compound interest formula: A = P(1 + r/n)^nt + C × [((1 + r/n)^nt − 1) / (r/n)]
Where P = principal, r = annual rate, n = compounds/year, t = years, C = monthly contribution.