Compound Interest Calculator
See how money grows over time with compound interest — and calculate the true cost of starting your investments later vs starting now. Every year of delay matters.
Over 20 years, your $130,000 in contributions grows to $284,670.
Compound growth alone adds $154,670 — that is the cheapest yield in finance.
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Starting to invest at 25 vs 35 — with the same $500/month — produces $2.1 million less at retirement. Compound interest is the only financial force that accelerates rather than slows over time.
Frequently Asked Questions
Everything you need to know.
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Why This Matters
Starting to invest at 25 vs 35 — with the same $500/month — produces $2.1 million less at retirement. Compound interest is the only financial force that accelerates rather than slows over time.
How to Use It
- 1Enter your starting balance (can be $0)
- 2Set your monthly contribution amount
- 3Enter expected annual return (S&P 500 historical: ~10%)
- 4Adjust time horizon to see the impact of starting earlier
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