Compound Interest Calculator
Grow a lump sum plus regular contributions at any compounding frequency.
Enter your values
Enter the starting amount in $.
Enter the monthly contribution in $.
Enter the annual return in %.
Enter the years in years.
Choose one of: Monthly, Quarterly, Yearly, Daily.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- Future value
- $170,619.05
- Total contributed
- $70,000.00
- Interest earned
- $100,619.05
- Growth multiple
- 2.44×
Quick answer
Compound interest pays interest on previously earned interest, so a balance grows as A = P(1 + r/n)^(nt) plus the future value of contributions.
A = P(1 + r/n)^(nt)
At a glance
| What it does | Grow a lump sum plus regular contributions at any compounding frequency. |
|---|---|
| Category | Finance |
| Inputs needed | Starting amount, Monthly contribution, Annual return, Years, Compounding |
| Main output | Future value |
| Formula | A = P(1 + r/n)^(nt) |
| Cost | Free — no sign-up, no download |
How to use the Compound Interest Calculator
- 1Enter your starting balance and monthly contribution.
- 2Set an expected annual return and time horizon.
- 3Read the future value and interest earned.
Inputs explained
- Starting amount($)
- Enter the starting amount in $.
- Monthly contribution($)
- Enter the monthly contribution in $.
- Annual return(%)
- Enter the annual return in %.
- Years(years)
- Enter the years in years.
- Compounding
- Choose one of: Monthly, Quarterly, Yearly, Daily.
Worked example
Using the values the calculator loads with:
Inputs
- Starting amount10000 $
- Monthly contribution250 $
- Annual return7 %
- Years20 years
- CompoundingMonthly
Results
- Future value$170,619.05
- Total contributed$70,000.00
- Interest earned$100,619.05
- Growth multiple2.44×
Frequently asked questions
What return should I assume?
A diversified stock portfolio has historically returned about 7% a year after inflation, but any single decade can be far higher or lower.
Does compounding frequency matter much?
Less than people expect. At 7%, daily versus yearly compounding differs by roughly a quarter of a percent per year.
What do I need to enter into the Compound Interest Calculator?
Just 5 values: starting amount, monthly contribution, annual return, years, compounding. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Compound Interest Calculator work out the answer?
Compound interest pays interest on previously earned interest, so a balance grows as A = P(1 + r/n)^(nt) plus the future value of contributions. It applies the formula A = P(1 + r/n)^(nt) and shows the working so you can check each step by hand.
Is the Compound Interest Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.