Compound Interest Calculator: See Your Money Grow
Future Value
$300,851
Total Invested
$130,000
Interest Earned
$170,851
Growth Over Time
Year 1
Total: $16,919
Year 2
Total: $24,339
Year 3
Total: $32,294
Year 4
Total: $40,825
Year 5
Total: $49,973
Year 6
Total: $59,782
Year 7
Total: $70,299
Year 8
Total: $81,578
Year 9
Total: $93,671
Year 10
Total: $106,639
Year 11
Total: $120,544
Year 12
Total: $135,455
Year 13
Total: $151,443
Year 14
Total: $168,587
Year 15
Total: $186,971
Year 16
Total: $206,683
Year 17
Total: $227,820
Year 18
Total: $250,486
Year 19
Total: $274,790
Year 20
Total: $300,851
| Year | Balance | Contributions | Interest |
|---|---|---|---|
| 1 | $16,919 | $16,000 | $919 |
| 3 | $32,294 | $28,000 | $4,294 |
| 5 | $49,973 | $40,000 | $9,973 |
| 7 | $70,299 | $52,000 | $18,299 |
| 9 | $93,671 | $64,000 | $29,671 |
| 11 | $120,544 | $76,000 | $44,544 |
| 13 | $151,443 | $88,000 | $63,443 |
| 15 | $186,971 | $100,000 | $86,971 |
| 17 | $227,820 | $112,000 | $115,820 |
| 19 | $274,790 | $124,000 | $150,790 |
| 20 | $300,851 | $130,000 | $170,851 |
Compound interest is the most powerful force in investing. This calculator shows you exactly how your money grows when interest earns interest. Enter your initial investment, monthly contributions, expected return rate, and time horizon to see your future wealth.
How to Use This Calculator
- Enter your initial investment amount (the money you have now)
- Add your planned monthly contribution (what you'll add regularly)
- Set your expected annual interest rate (7% is a common long-term estimate)
- Choose your investment time period in years
- Select how often interest compounds (monthly is most common)
- View your projected future value and interest earned
Real Example: The Power of Starting Early
Person A: Starts at 25
- Invests $300/month for 40 years
- Total contributed: $144,000
- At 7% return: $791,957
Person B: Starts at 35
- Invests $300/month for 30 years
- Total contributed: $108,000
- At 7% return: $365,991
Starting 10 years earlier with the same monthly investment results in $425,966 more — more than double the final amount. Time is your greatest asset.
Why Calculate Compound Interest?
- Set realistic goals — Know how much you need to save monthly to reach your target
- Compare scenarios — See how different rates or contributions affect your outcome
- Plan retirement — Calculate if you're on track for your retirement number
- Stay motivated — Visualize your future wealth to maintain saving discipline
Frequently Asked Questions
What is compound interest?
Compound interest is interest calculated on both the initial principal and the accumulated interest from previous periods. This creates exponential growth over time, making it more powerful than simple interest.
How often should interest compound?
More frequent compounding leads to higher returns. Daily compounding yields slightly more than monthly, which yields more than annually. However, the difference is often small for typical interest rates.
What is a realistic annual return rate?
The S&P 500 has historically returned about 10% annually before inflation, or about 7% after inflation. Conservative investments like bonds typically return 3-5%. High-yield savings accounts offer 4-5% in 2024.
How accurate is this calculator?
This calculator provides accurate mathematical projections based on your inputs. Real investment returns vary year to year and are not guaranteed. Use this as a planning tool, not a guarantee of future results.
Does this account for taxes?
No, this calculator shows pre-tax growth. Actual returns depend on your account type (401k, IRA, taxable) and tax situation. Tax-advantaged accounts let you keep more of your gains.