📈 Compound Interest Calculator
Calculate how your money grows with compound interest over time.
Compound Interest Calculator — Calculate Investment Growth Over Time
Our free compound interest calculator helps you project how your investments grow with the power of compounding. See your future value, total contributions, and interest earned in seconds.
📐 How Compound Interest Works
Compound interest earns returns on both your initial principal AND accumulated interest. The formula is:
A = P(1 + r/n)^(nt) + PMT × [(1 + r/n)^(nt) – 1] / (r/n)
Where: P = principal, r = annual rate, n = compounds per year, t = years, PMT = monthly contribution.
📊 Investment Growth Examples (7% Annual Return)
| Monthly | 10 Years | 20 Years | 30 Years |
|---|---|---|---|
| $100 | $17,308 | $52,093 | $121,997 |
| $500 | $86,540 | $260,463 | $609,986 |
| $1,000 | $173,080 | $520,926 | $1,219,971 |
🔑 Key Factors Affecting Compound Growth
- Time: The earlier you start, the more dramatic the compounding effect
- Interest Rate: Higher returns accelerate growth exponentially
- Contribution Amount: Regular contributions significantly boost results
- Compounding Frequency: Daily compounding yields slightly more than annual
❓ Frequently Asked Questions
What is the Rule of 72?
Divide 72 by your annual interest rate to estimate how many years it takes to double your money. At 7%, money doubles in ~10.3 years.
Is compound interest better than simple interest?
Yes! Compound interest earns returns on returns. Over 30 years at 7%, $10,000 grows to $76,123 with compounding vs $31,000 with simple interest.
How much should I invest monthly?
Financial experts recommend investing 15-20% of your income. Even small amounts like $100/month can grow to over $120,000 in 30 years at 7%.
Does compounding frequency matter?
Daily compounding yields slightly more than annual, but the difference is small. At 7%, $10,000 over 20 years: daily = $40,546 vs annual = $38,697.