The formula used in the compound interest calculator is A P 1rnnt A the future value of the investment P the principal investment amount r the interest rate decimal. To calculate annual compound interest multiply the original amount of your investment or loan or principal by the annual interest rate. I for the third half-year.
The compound or effective annual interest rate is either paid annually or otherwise adjusted for compound interest effects.
Following is the formula for calculating compound interest when time period is specified in years and interest rate in per annum. 1 Compute the compound interest on 12000 for 2 years ate 20 pa. I for the first half-year P for the second half-year Rs. 10000 for 1½ years at 20 per annum interest being payable half-yearly.