What is the Compound Interest Calculator?
The compound interest calculator is a free online tool that helps you work out compound interest quickly and accurately. It uses the standard formula A = P x (1 + r/n)^(n x t); Interest = A - P and shows the result instantly as you type, along with a full breakdown so you can see exactly how the answer was reached.
How to use this calculator
- Enter the principal.
- Enter the annual rate.
- Enter the time in years.
- Choose how often interest compounds.
- See the maturity amount and interest earned.
Formula used
A = P x (1 + r/n)^(n x t); Interest = A - PExplanation of each input
- Principal amount โ the principal amount used in the calculation.
- Annual interest rate (%) โ the annual interest rate used in the calculation.
- Time period (years) โ the time period used in the calculation.
- Compounding frequency โ the compounding frequency used in the calculation.
Understanding your result
- Total interest โ the calculated total interest.
- Maturity amount โ the calculated maturity amount.
Step-by-step calculation
For the example values P = 100000, r = 8%, t = 5y, yearly:
- Apply the formula:
A = P x (1 + r/n)^(n x t); Interest = A - P - Substitute the values: A = 100000 x (1.08)^5
- Result: Maturity about 146933; interest about 46933
Worked example
| Inputs | P = 100000, r = 8%, t = 5y, yearly |
|---|---|
| Working | A = 100000 x (1.08)^5 |
| Result | Maturity about 146933; interest about 46933 |
Benefits and practical uses
This calculator saves you time and reduces errors when you need compound interest. It is useful for students, professionals and anyone who wants a fast, reliable answer without manual calculation. Results update instantly, work in your browser and can be copied or shared in one click.
Assumptions and limitations
- Constant rate.
- No withdrawals or extra deposits during the period.
Frequently asked questions
Why does compounding frequency matter?
The more often interest compounds, the more you earn, because each period's interest itself earns interest.
What is the rule of 72?
Divide 72 by the annual rate to estimate the years needed to double your money.