How to use the Compound Interest Calculator
- Enter your starting amount.
- Enter the yearly interest rate and the number of years.
- Choose how often interest is added (yearly to daily).
- Add a monthly amount if you will keep investing, then read the result.
How it's calculated
Show the formula
A = P × (1 + r ÷ n)n × t
P = starting amount · r = yearly rate · n = times per year · t = years
P = starting amount · r = yearly rate · n = times per year · t = years
More frequent compounding earns slightly more: 12% compounded monthly is an effective 12.68% a year. Monthly additions are added at the end of each month.
Worked example
These are the example numbers the calculator opens with. Change any of them above to see your own result.
You enter
| Starting amount | Rs 5,00,000 |
|---|---|
| Interest rate (per year) | 12% |
| Years | 10 years |
| Compounding | Monthly |
| Monthly addition | Rs 0 |
You get
| Final amount | Rs 16,50,193 |
|---|---|
| Total put in | Rs 5,00,000 |
| Interest earned | Rs 11,50,193 |
| Effective yearly rate | 12.68% |
| Money multiplied by | 3.3× |
Tips
- The rule of 72: divide 72 by the rate to see roughly how many years it takes to double your money.
- Compare offers by their effective yearly rate, not the headline rate.
Frequently asked questions
What is compound interest?
It is interest earned on your money plus on the interest already added. Over many years it makes savings grow much faster.
Does monthly compounding really make a difference?
A little: 12% compounded monthly is an effective 12.68% a year, compared with 12% compounded yearly.
How long does it take to double my money?
At 12% a year it takes about 6 years (72 ÷ 12).