Financial
Compound Interest Calculator
Project growth of savings with regular contributions and compounding.
Inputs
Compound Interest Calculator
Result
Future value
$300,850.72
- Total contributed
- $130,000.00
- Interest earned
- $170,850.72
How it's calculated
FV = P(1+r)^n + PMT · ((1+r)^n − 1)/r
Common questions
Are taxes included?
No — this is pre-tax growth. Adjust the annual return down to model after-tax.
Why compounding matters
Compound interest earns interest on the interest you've already earned. Over long horizons the curve bends sharply upward — most of the final balance comes from growth, not contributions. That's why starting early beats contributing more later.
Use this alongside the Retirement Calculator to project a nest egg, and the Inflation Calculator to see the future value in today's purchasing power.
Realistic assumptions
The default 7% return is a rough long-run stock-market average before taxes and fees. Adjust downward for a mixed portfolio, bonds, or after-tax modeling. For historical comparisons, plug your actual start and end balances into the Investment Return Calculator to get the annualized (CAGR) return.
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