Compound Interest Calculator
See how savings and investments grow with compound interest and regular monthly deposits. Year-by-year growth table. Free and instant.
| Year | Total deposits | Total interest | Balance |
|---|---|---|---|
| 1 | $12,400.00 | $919.98 | $13,319.98 |
| 2 | $14,800.00 | $2,115.52 | $16,915.52 |
| 3 | $17,200.00 | $3,609.48 | $20,809.48 |
| 4 | $19,600.00 | $5,426.64 | $25,026.64 |
| 5 | $22,000.00 | $7,593.83 | $29,593.83 |
| 6 | $24,400.00 | $10,140.09 | $34,540.09 |
| 7 | $26,800.00 | $13,096.88 | $39,896.88 |
| 8 | $29,200.00 | $16,498.29 | $45,698.29 |
| 9 | $31,600.00 | $20,381.21 | $51,981.21 |
| 10 | $34,000.00 | $24,785.61 | $58,785.61 |
About the Compound Interest Calculator
Watch your money grow. Enter a starting amount, a regular monthly deposit, an expected annual return and how often interest compounds to see your future balance and how much of it comes from interest rather than your own deposits.
How to use it
- Enter your starting balance and monthly contribution.
- Enter the expected annual interest rate or return.
- Choose how many years and how often interest compounds.
- Review the final balance and the year-by-year table.
How compound growth is calculated
The calculator works month by month. Your balance earns interest at the effective monthly rate for your chosen compounding frequency, and your monthly contribution is added at the end of each month. Interest earned is then included in the next month's balance, which is what makes growth accelerate over time.
Worked example
Start with 100,000, add 10,000 every month and earn 10% a year compounded monthly. After 10 years you will have deposited 1,300,000, and the balance will be about 2,319,154. More than 1,019,000 of that — over 40% — is interest rather than money you put in.
Run the same plan for 20 years and the interest overtakes your deposits by a wide margin. Time in the market matters more than the exact rate.
Using the result wisely
Fixed deposits and savings accounts have known rates, so the projection is reliable. Shares and funds go up and down, so use a conservative long-term average and remember that inflation reduces what the future balance can buy. Fees and taxes on interest also reduce real returns.
Frequently asked questions
What is compound interest?
Compound interest is interest earned on both your original money and the interest it has already earned. Over long periods this snowball effect can make interest a larger share of your balance than your deposits.
Does compounding frequency matter much?
More frequent compounding gives a slightly higher return. Monthly versus yearly compounding at 10% adds roughly half a percentage point a year.
Are returns guaranteed?
Only for fixed products such as fixed deposits. Investment returns vary from year to year, so treat the result as an estimate.