Compound Interest Calculator
Formula
A = P(1 + r/n)^(nt)
Where: A = Final amount, P = Principal, r = Rate, n = Compounding frequency, t = Time
About This Calculator
Use the compound interest calculator when you want faster calculations with a clear method behind every result.
Project long-term balance growth from principal, contribution cadence, interest rate, and time horizon to compare realistic saving trajectories.
If your workflow expands, pair this calculator with Retirement Savings Calculator and Investment Compound Growth Calculator (Dollar Cost Averaging) to cross-check assumptions and build a stronger analysis chain.
Formula
A = P(1 + r/n)^(nt) + PMT * [((1 + r/n)^(nt) - 1) / (r/n)]
Example Calculation
The worked example below demonstrates how the input fields translate into the final output. Use it as a quick validation pass before entering your own numbers.
- principal: 10000
- monthlyContribution: 300
- annualRatePercent: 7
- years: 20
Explanation of Results
Result Interpretation
At 7% annual growth with steady monthly investing, compounding turns a modest starting balance into a six-figure portfolio over 20 years.
FAQ
Should I use nominal or expected real return?
Use nominal return for account balance forecasting and inflation-adjusted return when planning future purchasing power.
Why does contribution timing matter?
Contributing earlier in each period gives money more time to compound, which can materially increase final balance over long horizons.
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See Also
Other calculators in Personal Finance
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Compound Interest Calculator with Variable Contributions
Emergency Fund Months Calculator
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