Finance Tools
Compound Interest Calculator
Compound interest calculator for principal, annual rate and years, with optional monthly deposits. Switch to reverse to find the starting amount or monthly contribution for a future target.
Calculation
Investment details
Results
Future value
270,704.15
Principal
100,000
Contributions
0
Interest earned
170,704.15
Years
10
- Principal
- Contributions
- Interest
These figures are estimates. Actual investment returns can vary, and this is not financial advice. For a reducing-balance loan, use the Loan Calculator or the EMI Calculator. The compound interest guide walks through the forward formula.
Year-by-year growth
| Year | Contributions | Interest | Balance |
|---|---|---|---|
| 1 | 0 | 10,471.31 | 110,471.31 |
| 2 | 0 | 22,039.1 | 122,039.1 |
| 3 | 0 | 34,818.18 | 134,818.18 |
| 4 | 0 | 48,935.41 | 148,935.41 |
| 5 | 0 | 64,530.89 | 164,530.89 |
| 6 | 0 | 81,759.43 | 181,759.43 |
| 7 | 0 | 100,792.02 | 200,792.02 |
| 8 | 0 | 121,817.56 | 221,817.56 |
| 9 | 0 | 145,044.76 | 245,044.76 |
| 10 | 0 | 170,704.15 | 270,704.15 |
About this tool
This compound interest calculator grows a principal (starting amount) at a stated annual rate. Interest is added back each period, so later interest is charged on a larger balance. Optional monthly deposits sit on top of that. Switch to Reverse Compound Interest when you already know the future target and need today’s investment, or the monthly contribution that reaches it. It is an investment growth calculator, not a loan EMI.
How to use
- Enter principal, annual rate and number of years.
- Choose how often interest compounds.
- Optionally add a monthly contribution.
- Read future value, interest earned and the year-by-year table.
- Or switch to Reverse Compound Interest to solve for the starting amount or monthly contribution that reaches a target.
Compound interest formula
Each month the balance is multiplied by (1 + r/n)^(n/12), then the monthly contribution is added. r is the annual rate as a decimal and n is compounds per year (1, 2, 4, 12 or 365). That monthly factor matches the compounding frequency you pick. With no extra deposits, this is the usual compound interest formula A = P(1 + r/n)^(nt) applied month by month.
Worked example
Principal 100,000 at 10% compounded monthly for 10 years with no contributions grows to about 270,704. If you also add 5,000 a month, both the deposits and the interest accumulate.
Reverse Compound Interest Calculator
Reverse compound interest starts from a future target and works backward. With no extra deposits, the starting amount is the present value P = A / (1 + r/n)^(nt): A is the target, r is the annual rate as a decimal, n is compounds per year and t is years. A target of 100,000 in 10 years at 7% needs 49,759.63 invested today if interest compounds monthly, or 50,834.93 if it compounds once a year. The monthly-contribution option uses the same end-of-month deposit rule as the growth calculator. From 10,000 already invested, that 100,000 target at 7% compounded monthly needs 461.64 added each month. Partial years round to the nearest month. These figures are estimates. Actual returns vary, and this is not financial advice.
Frequently asked questions
What is the compound interest formula?+
Without extra deposits: A = P(1 + r/n)^(nt), where P is principal, r is the annual rate as a decimal, n is compounds per year and t is years. This page applies that rate monthly, then adds any monthly contribution at the end of the month.
How does the reverse compound interest calculator work?+
It rearranges the same formula. With no extra deposits, the starting amount is P = A / (1 + r/n)^(nt). You can also solve for the monthly contribution that reaches a target from a starting amount you already have. Results are estimates, not a prediction of market returns.
Is this the same as EMI?+
No. Compound interest grows savings or an investment. EMI is a loan payment that shrinks a balance. Use the EMI Calculator for installments.
Are taxes or inflation included?+
No. The result is a nominal future value from the rate you enter. It is not financial advice.
Guides
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