Compound Interest Calculator
Results are estimates based on the values you enter. Recheck your inputs and assumptions before using the output for decisions.
Project future value with compounding and optional recurring contributions.
Compound Interest Calculator
Free online compound interest calculator to estimate how money grows when interest is earned on both the original amount and previously accumulated interest. This calculator is useful for savers, investors, students, finance planners, and anyone projecting future account value over time. Compound interest is one of the most important ideas in personal finance because growth can build on itself. Even moderate rates can produce much larger outcomes over long periods when earnings are reinvested. This calculator helps make that effect clear by turning starting balance, rate, time, compounding frequency, and optional recurring contributions into a projected future value.
This page uses five inputs. Starting amount means the initial balance. Annual return means the yearly interest or return rate. Years means the total investment or savings period. Compounds per year means how often interest is added during each year. Contribution each period means any recurring amount added every compounding period, such as a monthly deposit. Once those values are entered, the calculator shows future value, total contributions, and total growth. These outputs make it easier to distinguish how much of the final balance came from money deposited and how much came from the compound-interest effect itself.
The formula of compound interest
Periodic rate = Annual return / Compounds per year
Total periods = Years x Compounds per year
Growth of starting amount = Starting amount x (1 + Periodic rate) ^ Total periods
Growth of recurring contributions = Contribution each period x (((1 + Periodic rate) ^ Total periods – 1) / Periodic rate)
Future value = Growth of starting amount + Growth of recurring contributions
Total contributions = Starting amount + (Contribution each period x Total periods)
Total growth = Future value – Total contributions
Here starting amount means the initial principal, annual return means the yearly rate of growth, compounds per year means how many times growth is applied in one year, contribution each period means the recurring amount added at each compounding step, future value means the final projected balance, total contributions means the total amount personally added, and total growth means the amount created by compounding beyond contributions.
Solved Example
Example 1: Find the future value if the starting amount is $10,000, annual return is 8%, years are 10, compounds per year are 12, and the contribution each period is $0.
Solve: Future value = 10000 x (1 + 0.08 / 12) ^ 120 = $22,196.40
Total contributions = $10,000
Total growth = 22196.40 – 10000 = $12,196.40
Example 2: Find the result if the starting amount is $5,000, annual return is 6%, years are 5, compounds per year are 12, and the contribution each period is $100.
Solve: Starting amount growth = 5000 x (1 + 0.06 / 12) ^ 60 = $6,744.26
Contribution growth = 100 x (((1.005) ^ 60 – 1) / 0.005) = $6,977.00
Future value = 6744.26 + 6977.00 = $13,721.26
Total contributions = 5000 + (100 x 60) = $11,000
Total growth = 13721.26 – 11000 = $2,721.26
Example 3: Find the result if the starting amount is $20,000, annual return is 5%, years are 3, compounds per year are 4, and the contribution each period is $250.
Solve: Future value = 20000 x (1 + 0.05 / 4) ^ 12 + 250 x (((1.0125) ^ 12 – 1) / 0.0125) = $24,273.74
Total contributions = 20000 + (250 x 12) = $23,000
Total growth = 24273.74 – 23000 = $1,273.74
Table of compound interest calculator
| Starting Amount | Rate | Years | Contribution | Future Value |
|---|---|---|---|---|
| $5,000 | 6.00% | 5 | $100 / month | $13,721.26 |
| $10,000 | 8.00% | 10 | $0 | $22,196.40 |
| $20,000 | 5.00% | 3 | $250 / quarter | $24,273.74 |
| $50,000 | 7.00% | 8 | $0 | $87,309.22 |
How to use this compound interest calculator
Enter the starting amount in the proper input field. After that, enter the annual return, the number of years, and the compounding frequency. If you want to include regular additions, enter the contribution each period as well. Then click the calculate button. The calculator will show future value, total contributions, and total growth in the result box.
This calculator is useful when planning savings, investments, education funds, retirement balances, or any long-term growth target. Looking at total contributions beside total growth helps show whether the end result is coming mostly from the money you added or from the compounding effect itself. Over longer periods, compounding often becomes more important than the earliest users expect. That makes this calculator especially helpful for long-term planning and for comparing different contribution and rate scenarios.
When using the result, remember that this is a projection model based on a constant rate and regular compounding. Real returns can vary over time, and taxes, fees, withdrawal rules, and contribution timing may affect the final result. It is best used as an estimate and comparison tool rather than a guaranteed forecast. Even so, compound interest remains one of the clearest and most powerful ideas in finance because it shows how money can grow through reinvested earnings across time. This calculator gives a fast numerical view that supports savings planning, investing, retirement analysis, and financial education.