Compounding Calculator
Investment growth calculator with monthly contributions, compound frequency, and inflation-adjusted future value.
Compounding Calculator
Investment growth calculator with monthly contributions, compound frequency, and inflation-adjusted future value.
Formula reference
FV = PV(1+r/n)^(nt) + PMT × [((1+r/12)^(12t) - 1) / (r/12)]
Investment
Starting balance or loan amount before interest
Regular monthly deposit or investment
Annual percentage rate (APR)
Time horizon in years
Advanced
Adjusts real purchasing power
Formula
FV = PV(1+r/n)^(nt) + PMT × [((1+r/12)^(12t) - 1) / (r/12)]
Frequently Asked Questions
What is compound interest?▼
Interest earned on both principal and previously accumulated interest — exponential growth over time.
Why add monthly contributions?▼
Regular investing (dollar-cost averaging) often contributes more to long-term wealth than the initial lump sum.
What return rate should I use?▼
Historical S&P 500 average is ~10% nominal, ~7% after inflation. Conservative planners use 6-7%.
What is inflation-adjusted value?▼
The purchasing power of your future balance expressed in today's dollars.
Does compounding frequency matter?▼
More frequent compounding yields slightly higher returns. Monthly vs daily difference is usually small.
Are taxes included?▼
No. Use tax-advantaged accounts (401k, IRA) for tax-deferred or tax-free growth.
Can I model withdrawals?▼
This calculator models accumulation only. Use a retirement withdrawal calculator for decumulation.
What is the Rule of 72?▼
Divide 72 by your return rate to estimate years to double your money. At 7%, money doubles in ~10 years.
Is this financial advice?▼
No. This is an educational tool. Consult a financial advisor for personalized planning.
How is monthly contribution compounded?▼
Contributions are modeled as end-of-month deposits at the monthly equivalent of your annual rate.
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How This Calculator Works
This Compound Interest Calculator uses industry-standard formulas to produce detailed, actionable results. Enter your values in the grouped sections above, then click **Calculate** to see metrics, breakdowns, and insights.
Formula Reference
FV = PV(1+r/n)^(nt) + PMT × annuity factor
Interpreting Your Results
Review highlighted metrics first, then check any amortization tables or insight notes below the results. Adjust inputs to compare scenarios — all calculations run instantly in your browser.