Compound Interest Calculator
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How to use Compound Interest Calculator
- Enter the starting amount.
- Enter the annual rate, years and compounding frequency.
- Read the final balance and interest earned.
Common uses
- Projecting savings growth.
- Comparing compounding frequencies.
- Teaching how interest compounds.
About this tool
See how a sum grows with compound interest: A = P × (1 + r ÷ n)^(n × t). Enter the principal, the annual rate, the number of years and how many times a year interest compounds. This models a single starting amount with no extra contributions, taxes or fees.
Worked example
1,000 invested at 5% a year, compounded yearly for 10 years, grows to about 1,628.89. Without compounding (simple interest) it would be 1,500. More frequent compounding, such as monthly, adds a little more.
Common problems and fixes
- The result looks too high.
- Check that the rate is annual and the period is in years, not months.
- Inflation and fees are ignored.
- The result is nominal. Real returns are lower after inflation, taxes and fees.
- Returns are not guaranteed.
- Investments vary from year to year. Use the figure as an illustration, not a forecast.
Next steps
Frequently asked questions
What is the formula?
A = P × (1 + r/n)^(n×t).
Does more frequent compounding help?
Slightly: monthly compounding yields a little more than yearly at the same rate.
Does it include deposits or taxes?
No, it models a single starting amount.
Are my files uploaded to a server?
No. Everything runs inside your browser on your own device, so your files and text are never sent anywhere.
Is it really free?
Yes. There is no sign-up, no watermark and no limit on how often you use it.
Does it work on my phone?
Yes. It works in any modern browser on phones, tablets and computers. Very large files may be slow on older phones.