Compound Interest Calculator
See exactly how your money grows with compound interest — choose any compounding frequency and see the power of time.
✔ All Compounding Frequencies📐 Formula Shown
📈 Compound Interest Calculator
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Future Value
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After 20 years
Total Interest Earned
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Total Contributions
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Interest % of Total
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The Power of Compound Interest
Compound interest is interest calculated on both the initial principal and the accumulated interest from previous periods. Albert Einstein allegedly called it the "eighth wonder of the world" — whether or not he said it, the math is remarkable: $10,000 invested at 8% for 40 years grows to over $217,000 with no additional contributions.
📐 Compound Interest Formula
A = P(1 + r/n)^(n×t) + contributions
A= Final amount
P= Principal (initial investment)
r= Annual interest rate (decimal)
n= Compounding frequency per year
t= Time in years
📝 Example — $10,000 at 8% monthly for 20 years:
A = $10,000 × (1 + 0.08/12)^(12×20)
A = $10,000 × (1.006667)^240
A = $10,000 × 4.9268 = $49,268
Frequently Asked Questions
Simple interest is calculated only on the principal: Interest = P × r × t. Compound interest is calculated on the principal plus all previously earned interest. Over long periods, compound interest grows exponentially while simple interest grows linearly. For a $10,000 investment at 8% over 30 years: simple interest = $24,000 profit; compound interest = $90,627 profit.
More frequent compounding produces slightly higher returns. Daily compounding versus annual compounding on $10,000 at 10% for 10 years: daily = $27,179; annual = $25,937 — a difference of $1,242. For most investors, the difference between daily and monthly compounding is negligible compared to factors like contribution amount and investment timeline.
⚠️ Disclaimer Estimates for informational purposes only. Not legal or financial advice. Consult a qualified professional.