Finance
Compound Interest Calculator
Estimate future value using compounding frequency, annual return, and monthly deposits.
Calculator
Results
- Future value$248,758.05
- Total contributions$106,000.00
- Interest earned$142,758.05
Formula
FV = P(1 + r/m)(mt) + C × ((1 + r/m)(mt) − 1) ÷ (r/m), where P is principal, r is annual rate, m is compounds/year, t is years, and C is per-period contribution.
Use this formula with the live inputs above to test scenarios instantly.
Assumptions
- Returns are constant and compounded at a fixed frequency.
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How this formula works
Compound growth combines two engines: reinvested returns and recurring contributions. The first term in the equation grows your starting principal, while the second term accumulates a stream of deposits over the same compounding horizon.
This framing is useful for long-term investing because it separates how much of your future value comes from contributions versus growth. You can quickly test sensitivity to return assumptions, contribution amount, and investment duration.
References & citation
Use these references when documenting assumptions, and copy the block below when citing this calculator.
- What is a mortgage?
Consumer Financial Protection Bureau
Explains principal, interest, and repayment concepts used in mortgage formulas.
- Compound Interest Calculator and Learning Resources
U.S. Securities and Exchange Commission (Investor.gov)
Provides compounding intuition and long-term growth examples.