Compound Interest Calculator Calculators
See how savings grow with regular contributions and compounding.
Compound Interest Calculator is a free online tool that see how savings grow with regular contributions and compounding. It runs entirely in your web browser using plain JavaScript, so files are processed on your own device and never uploaded to a server. There is no sign-up, no file size limit imposed by the site, no watermark and no paid tier.
- Price
- Free — no account, no quota, no watermark
- Category
- Calculators
- Where it runs
- In your browser, on your device
- Files uploaded
- None
- Technology
- plain JavaScript
- Settings
- 6
- Works offline
- Yes, after the first visit
About Compound Interest Calculator
The starting amount compounds at your chosen frequency, while monthly contributions are grown using an equivalent monthly rate so the two parts combine correctly. The year-by-year table exists because compounding is genuinely hard to intuit — most of the growth arrives in the final third, which is exactly the part people give up before reaching.
How to use it
- Enter starting amount, monthly contribution and annual return.
- Adjust the remaining 3 settings if the defaults do not fit your case.
The 6 settings
| Setting | What it does | Default |
|---|---|---|
| Starting amount | A numeric value. | 5000 |
| Monthly contribution | A numeric value. | 250 |
| Annual return | A numeric value. | 7% |
| Years | Range 1–80. | 20 |
| Compounds | Choose from 4: Monthly, Quarterly, Annually, Daily. | Monthly |
| Currency | Choose from 7: USD $, GBP £, EUR €, INR ₹, AUD A$, CAD C$…. | USD $ |
Under the hood
| Runs on | plain JavaScript — runs the whole thing |
| Controls | Starting amount, Monthly contribution, Annual return, Years, Compounds, Currency |
Questions
Does compounding frequency matter much?
Less than people expect. At 7%, moving from annual to monthly compounding adds about 0.23 percentage points of effective yield. Contribution size and time invested dominate everything else.
Is this before or after inflation?
Before. Enter a real rate — nominal return minus expected inflation, so roughly 4–5% rather than 7% for equities — if you want the answer in today's money.
What does the compounds option change?
It offers 4 choices — Monthly, Quarterly, Annually and Daily. The default is Monthly, which suits most cases; change it when your input or your destination calls for something specific.
What are the limits on years?
It accepts 1 to 80, starting at 20.
Is the arithmetic exact?
It uses double-precision floating point — about 15 significant figures, far more than the inputs justify. Displayed rounding is cosmetic; the underlying numbers are not rounded between steps, so chained results do not drift.