Compound Interest Calculator
The compound interest calculator projects how your trading account grows over time when you reinvest profits and add regular contributions. Compounding is the most powerful force in wealth building — a consistent 1–2% monthly return, compounded over years, can turn a modest account into a substantial portfolio. This calculator includes a visual chart of your projected growth.
Ending Balance
$148,023
Total Contributed
$70,000
Total Interest Earned
$78,023
Growth Multiple
14.80×
How to use this calculator
- 1
Enter your starting balance
Your current account value in dollars.
- 2
Set your monthly contribution
How much you plan to add to your account each month. Enter 0 if you're not adding funds.
- 3
Enter your annual rate of return
Your expected yearly return. Be realistic — 12–20% annual is achievable for skilled traders. Divide your target monthly return by 12 for the annualized estimate.
- 4
Set the number of years
The time horizon for your projection.
- 5
Read the results and view the chart
See your ending balance, total contributions, and interest earned — with a visual growth chart.
Formula
Balance (month n) = Balance(n-1) × (1 + monthly rate) + monthly contribution
Monthly Rate = Annual Rate ÷ 12
Total Interest = Ending Balance − Total ContributionsEach month, the previous balance grows by the monthly interest rate, and then your contribution is added. This iterative process is what creates the exponential growth curve. Note that the order matters — interest accrues on the balance before the contribution, though the difference is negligible over time.
Worked Example
Starting balance: $10,000 Monthly contribution: $500 Annual rate: 12% (1% per month) Time period: 10 years (120 months) Month 1: $10,000 × 1.01 + $500 = $10,600 Month 2: $10,600 × 1.01 + $500 = $11,206 ... Month 120 (Year 10): ~$131,501 Total contributed: $10,000 + (120 × $500) = $70,000 Total interest earned: ~$61,501 Growth multiple: ~13.2×
Frequently Asked Questions
Related Tools
Sponsored
TradingView— free charts for forex, crypto & stocks
Used by 60 million traders. Free plan available, no credit card needed.