Compound Interest Calculator
Compute future value of an investment with compound interest, monthly contributions, and any compounding frequency.
Inputs
Future Value
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Compound interest is the eighth wonder
A consistent monthly investment compounding at 7% doubles every ~10 years. The math feels modest year to year — until decade three, when the curve goes vertical. The lesson: start early, stay consistent.
Frequently Asked Questions
Is 7% realistic?
Long-run S&P 500 returns are around 10% nominal, 7% real (after inflation). 7% is a conservative real-return assumption for retirement planning.
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