Compound Interest Calculator
See what a starting amount plus steady monthly investing grows into — and how much of it is interest doing the work.
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Assumes monthly compounding at a constant return — real markets move unevenly. Long-term stock-market averages are commonly cited around 7–10% annually before inflation, but past performance never guarantees the future. Educational tool — not individualized advice.
The takeaway most people miss
Run 10 vs. 30 years with the same monthly amount — the last decade earns more than the first two combined. Compounding rewards time more than timing, which is why starting small now beats starting big later.
New to this? Start here: How to start investing with $100.