Compound Interest Calculator
See how your money grows with compound interest. Model daily, monthly, quarterly, or yearly compounding — complete with an interactive growth chart and a full year-by-year breakdown.
Compound Interest
Investment growth calculator
INITIAL INVESTMENT
INTEREST & TIME
ADDITIONAL CONTRIBUTIONS (OPTIONAL)
💡 Rule of 72
At 7% annual rate, your money doubles every 10.3 years.
Formula: 72 ÷ interest rate = years to double
Final Balance
$19,672
$10,000
Principal
$9,672
Total Interest
96.7%
Total Return
- Initial Principal
- $10,000
- Additional Contributions
- $0
- Total Interest Earned
- $9,672
- Final Balance
- $19,672
- Effective Annual Rate
- 7.00%
- vs Simple Interest
- +$2,672 more
Balance Breakdown
- Principal
- Interest Earned
Investment Growth Over Time
Year-by-Year Breakdown
| Year | Start Balance | Interest | Contributions | End Balance |
|---|---|---|---|---|
| Year 1 | $10,000 | +$700 | +$0 | $10,700 |
| Year 2 | $10,700 | +$749 | +$0 | $11,449 |
| Year 3 | $11,449 | +$801 | +$0 | $12,250 |
| Year 4 | $12,250 | +$858 | +$0 | $13,108 |
| Year 5 | $13,108 | +$918 | +$0 | $14,026 |
| Year 6 | $14,026 | +$982 | +$0 | $15,007 |
| Year 7 | $15,007 | +$1,051 | +$0 | $16,058 |
| Year 8 | $16,058 | +$1,124 | +$0 | $17,182 |
| Year 9 | $17,182 | +$1,203 | +$0 | $18,385 |
| Year 10 | $18,385 | +$1,287 | +$0 | $19,672 |
What is Compound Interest?
Compound interest is often called the “eighth wonder of the world.” Unlike simple interest — calculated only on the principal — compound interest is calculated on both the principal AND the accumulated interest from previous periods, creating exponential rather than linear growth. Our compound interest calculator shows exactly how powerful this effect is over time. For building long-term wealth, also explore our investment calculator and retirement calculator.
📐 Compound Interest Formula
- A = Final amount
- P = Principal (initial investment)
- r = Annual interest rate (decimal)
- n = Compounding periods per year
- t = Time in years
Example: $10,000 at 7% for 10 years (annually): A = 10,000×(1.07)^10 ≈ $19,672
📊 Compounding Frequency Comparison
$10,000 at 7% for 10 years
| Annually | $19,672 |
| Quarterly | $19,898 |
| Monthly | $20,097 |
| Daily | $20,136 |
More frequent compounding earns slightly higher returns, but rate and time matter far more than frequency.
🚀 Power of Starting Early
Investing $5,000/year at 7% annual return, retiring at 65:
- Start at 25, retire at 65: ~$1,068,048
- Start at 35, retire at 65: ~$472,304
- Start at 45, retire at 65: ~$196,715
Starting 10 years earlier more than doubles your savings — time is your most valuable investing asset.
Use our retirement calculator to plan your specific goal.
🔄 Rule of 72
A quick mental math trick: divide 72 by your interest rate to find how many years it takes to double your money.
- At 4%: doubles in 18 years
- At 6%: doubles in 12 years
- At 8%: doubles in 9 years
- At 10%: doubles in 7.2 years
- At 12%: doubles in 6 years
The Rule of 72 applies to debt too — 24% APR credit card debt doubles in just 3 years.
— FAQ