Compound Interest Calculator
Calculate compound interest for any principal, rate, and time period. Includes a visual growth chart, year-by-year breakdown table, and support for different compounding frequencies.
Final Amount
$19,672
Total Interest
$9,672
Principal
$10,000
Growth Over Time
| Year | Balance | Year Interest | Total Interest |
|---|---|---|---|
| 1 | $10,700 | $700 | $700 |
| 2 | $11,449 | $749 | $1,449 |
| 3 | $12,250 | $801 | $2,250 |
| 4 | $13,108 | $858 | $3,108 |
| 5 | $14,026 | $918 | $4,026 |
| 6 | $15,007 | $982 | $5,007 |
| 7 | $16,058 | $1,051 | $6,058 |
| 8 | $17,182 | $1,124 | $7,182 |
| 9 | $18,385 | $1,203 | $8,385 |
| 10 | $19,672 | $1,287 | $9,672 |
How to Use
- Enter your initial investment (principal amount)
- Set the annual interest rate as a percentage
- Choose the investment period in years
- Select the compounding frequency (annually, monthly, quarterly, or daily)
- View your projected growth, total interest earned, and year-by-year breakdown
What Is Compound Interest?
Compound interest is interest calculated on both the initial principal and all previously accumulated interest. Unlike simple interest, which grows linearly, compound interest grows exponentially over time — a phenomenon Albert Einstein reportedly called the eighth wonder of the world.
The Rule of 72 provides a quick mental shortcut: divide 72 by the annual interest rate to estimate how many years it takes to double your money. At 8% annually, your investment roughly doubles every 9 years. A compound interest calculator shows the precise growth curve, factoring in contribution frequency, compounding intervals, and varying rates.
Popular Use Cases
Investment Planning
Project how a lump sum or recurring contributions will grow over 10, 20, or 30 years at different expected returns.
Retirement Savings
Estimate how much you need to save monthly to reach your retirement goal, and see the impact of starting earlier.
Comparing Accounts
Compare high-yield savings accounts, CDs, and bonds side by side to see which compounding frequency yields the best return.
Education Fund Growth
Plan college savings by calculating how regular deposits into a 529 plan or education fund compound over 18 years.
Compounding Tips
Start as Early as Possible
Time is the most powerful factor in compounding. Starting 10 years earlier can double your final balance even with smaller contributions.
Higher Frequency Helps
Monthly compounding outperforms annual compounding at the same rate. Daily compounding adds a smaller but still meaningful edge.
Use the Rule of 72
Divide 72 by the annual interest rate for a quick doubling estimate. At 6%, money doubles in about 12 years; at 12%, about 6 years.
Real vs Nominal Returns
Subtract the inflation rate from your nominal return to get real purchasing power growth. A 7% return with 3% inflation is really 4%.
Compounding Frequency Comparison
| Frequency | Times/Year | $10,000 at 8% for 10 Years | Total Interest |
|---|---|---|---|
| Annual | 1 | $21,589 | $11,589 |
| Quarterly | 4 | $22,080 | $12,080 |
| Monthly | 12 | $22,196 | $12,196 |
| Daily | 365 | $22,253 | $12,253 |