Compound Interest Calculator
Grow your savings with regular deposits
| Year | Deposits | Interest | Balance |
|---|---|---|---|
| 1 | $6,000 | $919 | $16,919 |
| 2 | $6,000 | $1,419 | $24,339 |
| 3 | $6,000 | $1,956 | $32,294 |
| 4 | $6,000 | $2,531 | $40,825 |
| 5 | $6,000 | $3,148 | $49,973 |
| 6 | $6,000 | $3,809 | $59,782 |
| 7 | $6,000 | $4,518 | $70,299 |
| 8 | $6,000 | $5,278 | $81,578 |
| 9 | $6,000 | $6,094 | $93,671 |
| 10 | $6,000 | $6,968 | $106,639 |
Compound Interest Calculator: See How Your Savings Grow
Our free compound interest calculator shows how a starting amount and regular deposits grow over time when interest is added to your balance and then earns interest itself. Enter your initial deposit, monthly contribution, interest rate and time period, and pick how often interest compounds. You get the future value, total deposits, total interest, the effective annual rate and a year-by-year breakdown. A second tab works out how long it takes to reach a savings goal.
Quick answer: $10,000 plus $500 a month at 7%, compounded monthly for 10 years, grows to $106,639. You put in $70,000, and the other $36,639 is interest. Leave it for 30 years and the balance reaches $691,150.
What Is Compound Interest?
Compound interest is interest calculated on your balance plus the interest already added to it. In the first year you earn interest on what you put in. In the next year you earn interest on that amount and on last year's interest. Over many years this snowball effect does most of the work, which is why starting early and adding regularly matters so much. Compare it with the plain interest calculator, which also covers simple interest and loans.
The Compound Interest Formula
The table shows the default example over different lengths of time. Notice how the interest column grows faster than the deposits column.
| Time | Total deposits | Interest earned | Final balance |
|---|---|---|---|
| 5 years | $40,000 | $9,973 | $49,973 |
| 10 years | $70,000 | $36,639 | $106,639 |
| 20 years | $130,000 | $170,851 | $300,851 |
| 30 years | $190,000 | $501,150 | $691,150 |
How Compounding Frequency Affects Growth
The more often interest is added, the more it earns, though the difference is modest. $10,000 at 7% for 10 years reaches $19,672 with annual compounding, $20,016 quarterly, $20,097 monthly and $20,136 daily. The effective annual rate captures this in one number, so it is the best way to compare accounts that compound differently.
Contributions, Timing and Yearly Increases
Regular deposits usually matter more than the starting amount. You can choose whether deposits are made at the end or the start of each month. Depositing at the start earns a month of extra interest on each contribution, which lifts the 10-year result from $106,639 to $107,144. You can also raise your contribution each year. Adding 3% more every year takes the same example to about $117,641.
Rule of 72 and Time to Goal
The Rule of 72 estimates how long money takes to double: divide 72 by the annual rate, so at 7% it is about 10.3 years. For an exact answer, use the Time to Goal tab. With the default numbers, you reach $100,000 in 9 years 6 months and $1,000,000 in 34 years 10 months. To plan with a target date, the savings calculator and the retirement calculator build on the same idea, and the investment calculator adds projections for different return scenarios.
Who Uses a Compound Interest Calculator?
Savers comparing accounts, investors projecting long-term growth, parents planning for education costs, people building a retirement fund, students learning how money grows, and anyone curious about the cost of waiting a few years to start. Results are estimates that assume a steady rate, and real returns vary. They are not financial advice.
How to Use This Compound Interest Calculator
Choose a tab
Use Future Value to see your balance after a set time, or Time to Goal to find how long a target takes.
Enter your starting amount
Add your initial deposit and the amount you plan to contribute each month.
Enter the rate and time
Use the annual interest rate and the number of years, or a target amount on the goal tab.
Pick the compounding options
Choose how often interest compounds and whether deposits are made at the start or end of the month.
Add increases and inflation (optional)
Raise contributions each year or enter an inflation rate to see today's buying power.
Click "Calculate Compound Interest"
See the results and open the yearly breakdown for a full table.