Compound Interest Calculator
Free compound interest calculator. See how your savings grow with compounding and regular monthly contributions, with the final balance, total contributions and interest earned.
Savings Details
Final Balance
$54,714
Growth Summary
Yearly Growth
| Year | Contributed | Interest | Balance |
|---|---|---|---|
| 1 | $12,400 | $801 | $13,201 |
| 2 | $14,800 | $1,834 | $16,634 |
| 3 | $17,200 | $3,115 | $20,315 |
| 4 | $19,600 | $4,662 | $24,262 |
| 5 | $22,000 | $6,495 | $28,495 |
| 6 | $24,400 | $8,633 | $33,033 |
| 7 | $26,800 | $11,100 | $37,900 |
| 8 | $29,200 | $13,918 | $43,118 |
| 9 | $31,600 | $17,114 | $48,714 |
| 10 | $34,000 | $20,714 | $54,714 |
How It Works
Enter your starting amount
Type the principal you are starting with and any additional amount you plan to add each month.
Set the rate and compounding
Enter the annual interest rate, choose how often interest compounds (annually, quarterly, monthly, daily) and the number of years.
Review the growth
See your projected final balance, how much you contributed in total and how much of the growth came from compound interest.
Compound interest is often called the most powerful force in finance because it lets your money earn money — and then lets those earnings earn money too. Over long periods this snowball effect can turn modest, consistent saving into a substantial balance, which is why starting early matters so much.
This calculator simulates your balance month by month, applying an equivalent monthly growth rate derived from your chosen compounding frequency and adding any regular contribution along the way. Use it to set realistic savings goals, compare accounts with different rates or compounding schedules, and see the long-term payoff of investing consistently.
Frequently Asked Questions
What is compound interest?
Compound interest is interest earned on both your original principal and on the interest already added to the balance. Because each period's interest itself earns interest, your money grows faster over time than it would with simple interest — an effect often called "interest on interest".
Does the compounding frequency matter?
Yes. The more often interest compounds — daily versus annually, for example — the more interest you earn at the same nominal rate, because gains are reinvested sooner. This calculator converts your chosen frequency into an equivalent monthly growth rate so the simulation stays accurate.
How do monthly contributions affect the result?
Adding a fixed amount each month dramatically increases your final balance, because every contribution then begins earning compound interest of its own. Even modest monthly deposits can outgrow a larger one-time deposit over a long enough period.
How is interest earned calculated here?
Interest earned is the final balance minus everything you put in — your starting principal plus the sum of all monthly contributions. It isolates the growth that came purely from compounding rather than from your own deposits.
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