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Calculate compound interest for savings, investments, or loans. See how compounding frequency affects returns with charts and a year-by-year breakdown.
In 10 years, your investment could be worth:
$19,419.00
$13,000.00
$6,419.00
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Everything you need to know
Compound interest is interest earned not only on your initial investment but also on all previously earned interest. In other words, it’s "interest on interest." When you invest money, your returns are reinvested, and those returns themselves generate new returns. This creates exponential growth rather than linear growth.
Albert Einstein allegedly called compound interest the "eighth wonder of the world" for good reason. While simple interest grows your money at a steady rate, compound interest accelerates over time, increasingly dramatically the longer you leave your money invested. This is why starting early and staying invested are two of the most powerful wealth-building principles in finance.
The difference between compound and simple interest becomes dramatic over long time periods. Over 30 years, the difference can be hundreds of thousands of dollars for substantial investments.
Using our compound interest calculator is straightforward:
Enter Your Initial Investment
Set Your Regular Contribution
Provide Your Expected Annual Return
Select Your Investment Period
Review Your Results
The formula for compound interest with regular deposits is:
A = P(1 + r/n)^(nt) + PMT × [((1 + r/n)^(nt) - 1) / (r/n)]
Where:
For simpler calculations with annual compounding:
A = P(1 + r)^t
Investment Details:
Calculation: A = $10,000 × (1 + 0.07)^10 A = $10,000 × 1.9672 Final Amount = $19,672
Interest Earned: $19,672 - $10,000 = $9,672
This means your money nearly doubles from interest alone!
Investment Details:
Calculation:
Breakdown:
Your contributions more than doubled from interest!
Scenario: Two people invest in a 7% annual return fund.
Investor A (Early Start):
Investor B (Late Start):
The Difference: By starting 10 years earlier with half the total contributions, Investor A ends up with $141,720 MORE! This is the power of time in compounding.
$1,000 initial investment, 20-year period, no additional contributions
| Interest Rate | Final Amount | Interest Earned |
|---|---|---|
| 2% | $1,486 | $486 |
| 4% | $2,191 | $1,191 |
| 6% | $3,207 | $2,207 |
| 8% | $4,661 | $3,661 |
| 10% | $6,727 | $5,727 |
A 2% increase in interest rate nearly doubles your final amount.
$5,000 initial investment, 6% annual return, 20 years
| Monthly Contribution | Final Amount | Total Invested | Interest Earned |
|---|---|---|---|
| $0 | $16,035 | $5,000 | $11,035 |
| $100 | $56,235 | $29,000 | $27,235 |
| $200 | $96,435 | $53,000 | $43,435 |
| $500 | $197,835 | $125,000 | $72,835 |
Regular $500/month contributions result in 73% of your final balance coming from interest!
$10,000 investment, 6% annual rate, 10 years
| Compounding Frequency | Final Amount |
|---|---|
| Annually | $17,908 |
| Quarterly | $18,140 |
| Monthly | $18,194 |
| Daily | $18,220 |
More frequent compounding creates slightly higher returns, but the difference is small for most consumer investments.
This quick estimation rule tells you how long it takes for your money to double:
Years to Double = 72 ÷ Interest Rate
At 8% interest: 72 ÷ 8 = 9 years to double At 6% interest: 72 ÷ 6 = 12 years to double
This simple rule demonstrates the impact of interest rate on compounding.
Compound interest can be calculated:
More frequent compounding means slightly higher returns, though the difference is typically small for typical interest rates (less than 0.5%).
The core principle behind compound interest is that money received today is worth more than money received in the future, because today’s money can be invested and earn returns. This is why starting early matters so much—each year of early contributions has more time to compound.
The longer your investment period, the more dramatic the compounding effect:
This is why retirement accounts (401k, IRA) with decades until withdrawal are so powerful.
FAQ
How accurate is this calculator? This calculator provides estimates based on inputs you provide. Actual results may vary based on market conditions and individual circumstances.
Can I rely on this for decisions? Use this as a planning tool, not financial advice. Consult professionals (financial advisor, tax accountant) before major decisions.
What assumptions does this use? Check the methodology section for assumptions. Market rates, inflation, returns, and other factors change and affect accuracy.
Interest Calculator • Investment Calculator • Savings Calculator
This calculator is provided for educational and informational purposes only. It is not financial, legal, tax, or investment advice. The results are estimates based on the assumptions and inputs you provide.
Actual results may differ significantly due to:
Please consult with a qualified financial advisor, tax professional, or attorney before making any financial decisions. Past performance does not guarantee future results. Always verify important calculations independently before relying on them.