Quick answer
Future value with compound interest and regular contributions. Enter initial amount, annual interest rate, years and compounding and the compound interest calculator returns future value, total deposited and interest earned.
Related tools: Investment Calculator: Project investment growth from a rate of return you choose. CAGR Calculator: Compound annual growth rate between two values. Retirement Calculator: Projected savings at retirement from your contributions and expected return.
How to use the Compound Interest Calculator
- Enter initial amount ($) (0 or more).
- Optionally, enter monthly contribution ($) (0 or more).
- Enter annual interest rate (%) (between 0 and 100).
- Enter years (between 0 and 100).
- Choose compounding: Monthly, Annually, Semi-annually, Quarterly, Daily and Weekly.
- Press Calculate to see the result, and use Reset to start again.
| Input | What to enter | Allowed values |
|---|---|---|
| Initial amount | A number, in $ | ≥ 0 |
| Monthly contribution (optional) | A number, in $ | ≥ 0 |
| Annual interest rate | A number, in % | ≥ 0, ≤ 100 |
| Years | A number | > 0, ≤ 100 |
| Compounding | Choose one: Monthly; Annually; Semi-annually; Quarterly; Daily; Weekly | Starts at Monthly |
Formula and method
Formula
A = P(1 + r/n)^(nt) + C·((1 + r/n)^(nt) − 1) ÷ (r/n)
IEEE-754 double precision; money shown to cents, rates to 4 decimals. Results are estimates, not financial advice.
Compound growth with end-of-period contributions equivalent to the monthly amount spread over each compounding period.
Worked examples
These examples are verified: each one is an automated test case that the live calculator must reproduce exactly.
Example 1
Inputs: Initial amount = 10000; Annual interest rate = 5; Years = 10; Compounding = Monthly.
| Result | Value |
|---|---|
| Future value | $16,470.09 |
| Total deposited | $10,000.00 |
| Interest earned | $6,470.09 |
Example 2
Inputs: Initial amount = 1000; Annual interest rate = 0; Years = 5; Compounding = Monthly.
| Result | Value |
|---|---|
| Future value | $1,000.00 |
| Total deposited | $1,000.00 |
| Interest earned | $0.00 |
The first line is the headline result (future value). Below it the compound Interest Calculator lists total deposited and interest earned, which describe the same case from other angles. IEEE-754 double precision; money shown to cents, rates to 4 decimals. Results are estimates, not financial advice.
What compounding does
With compound interest, interest earned in one period is added to the balance and earns interest itself in the next. The more often interest is compounded, the faster the balance grows, but the gain from daily instead of monthly compounding is small.
$10,000 at 5% for 10 years with different compounding
Every figure in this table comes from running this calculator, so it matches what the form returns.
| Compounding | Future value | Interest earned |
|---|---|---|
| Annually | $16,288.95 | $6,288.95 |
| Monthly | $16,470.09 | $6,470.09 |
| Daily | $16,486.65 | $6,486.65 |
What happens with invalid input
These messages are produced by the calculator itself, so you know what to fix.
- Annual interest rate: entering "-1" shows "Annual interest rate must be at least 0." beside that field and no result.
- Years: entering "0" shows "Years must be greater than 0." beside that field and no result.
Choosing between the Compound Interest Calculator and similar calculators
Each row shows what a related calculator on this site asks for and what it returns, so you can pick the one that matches your question.
| Calculator | You enter | It returns |
|---|---|---|
| [Investment Calculator](/finance/investment-calculator/) | initial amount, annual interest rate and years | Projected value |
| [CAGR Calculator](/finance/cagr-calculator/) | beginning value, ending value and years | CAGR |
| [Retirement Calculator](/finance/retirement-calculator/) | current age, retirement age and current savings | Projected savings at retirement |
| [401(k) Calculator](/finance/401k-calculator/) | annual salary, your contribution and employer matches this share of your contribution | Projected balance |
| [Simple Interest Calculator](/finance/simple-interest-calculator/) | principal, annual rate and time | Interest |
Background: interest, saving and investing
A nominal rate (APR) does not include the effect of compounding; the annual percentage yield (APY) does: APY = (1 + r/n)^n − 1. A 5% nominal rate compounded annually is 5.000%, semi-annually about 5.063%, quarterly about 5.095% and monthly about 5.116%, so more frequent compounding helps, but with diminishing returns.
The rate you enter in a projection is an assumption, not a promise: real returns vary and can be negative. Fees and taxes are not modelled unless the page says so.
Assumptions and limitations
- 0% rate gives simple accumulation
- Contributions optional
Results are estimates for planning, not financial advice. Lender terms, fees, taxes and rounding rules can change real figures, so confirm important numbers with your lender or a licensed adviser.
If a required value is empty, not a number, or outside its allowed range, the form marks that field with a message and shows no result instead of a misleading number. The automated checks deliberately try invalid entries for annual interest rate and years to confirm this.
Frequently asked questions
What does the Compound Interest Calculator calculate?
Future value with compound interest and regular contributions. It returns Future value, Total deposited and Interest earned.
What formula does the Compound Interest Calculator use?
A = P(1 + r/n)^(nt) + C·((1 + r/n)^(nt) − 1) ÷ (r/n). Compound growth with end-of-period contributions equivalent to the monthly amount spread over each compounding period.
What do I need to enter in the compound Interest Calculator?
You enter Initial amount ($), Annual interest rate (%), Years and Compounding. Optional: Monthly contribution ($).
How is the result rounded or limited?
IEEE-754 double precision; money shown to cents, rates to 4 decimals. Results are estimates, not financial advice. 0% rate gives simple accumulation.
What are the limits of this calculator?
0% rate gives simple accumulation. Contributions optional.
What does the “Compounding” option change?
It sets how the compound Interest is worked out. The choices are Monthly, Annually, Semi-annually, Quarterly, Daily and Weekly.
What is an example of a compound Interest result?
With initial amount 10000, annual interest rate 5, years 10 and compounding Monthly, the future value is $16,470.09.
Can I rely on this calculator for a decision?
Results are estimates for planning, not financial advice. Lender terms, fees, taxes and rounding rules can change real figures, so confirm important numbers with your lender or a licensed adviser. For this calculator in particular: 0% rate gives simple accumulation.
Related calculators
- Investment Calculator — Project investment growth from a rate of return you choose.
- CAGR Calculator — Compound annual growth rate between two values.
- Retirement Calculator — Projected savings at retirement from your contributions and expected return.
- 401(k) Calculator — Projected 401(k) balance with salary growth and employer match.
- Simple Interest Calculator — Interest earned or owed without compounding.
- Interest Per Day Calculator — Daily interest on a balance at an annual rate.
- Real Interest Rate Calculator — Inflation-adjusted interest rate using the exact Fisher relation.
- APY Calculator — Convert a nominal rate (APR) into the effective annual yield (APY).
Sources
- Standard time-value-of-money relations (e.g. Brealey, Myers & Allen, Principles of Corporate Finance)
Content last reviewed 2026-11-04. Formulas and worked examples are checked by automated tests against independently computed values.