Simple interest calculator help

 Settings Remark Interest rate (R) The interest rate (R) is expressed as percentage (%) per interest period. The interest rate may contain max two digits after its decimal point. The interest rate entered may contain a comma (,) or point (.) as a decimal point separator. Correct entered interest rates 5.25 5,25 4 Incorrect entered interest rates 5.041 You can choose between the following interest periods: day For example: 4.5% per day Every day the interest will be calculated on the principal amount for the specified time period (T). week For example: 4.5% per week Every week the interest will be calculated on the principal amount for the specified time period (T). two weeks For example: 4.5% per two weeks Every two weeks the interest will be calculated on the principal amount for the specified time period (T). half month For example: 4.5% per half month Every half month the interest will be calculated on the principal amount for the specified time period (T). month For example: 4.5% per month Every month the interest will be calculated on the principal amount for the specified time period (T). two months For example: 4.5% per two months Every two months the interest will be calculated on the principal amount for the specified time period (T). quarter For example: 4.5% per quarter Every quarter the interest will be calculated on the principal amount for the specified time period (T). half year For example: 4.5% per half year Every half year the interest will be calculated on the principal amount for the specified time period (T). year For example: 4.5% per year Every year the interest will be calculated on the principal amount for the specified time period (T). The interest rate (R) and time period (T) should be in the same time units such as weeks, months, years etc. If they differ the calculator will adjust the time period accordingly. Example 1: How time period will be adjusted: Interest rate = 5% per month Time period = 7 weeks 52 weeks equals 12 months equals 1 year Thus 7 weeks equals (7*12)/52 = 1.615384 months Example 2: How time period will be adjusted: Interest rate = 5% per two weeks Time period = 2 quarters 4 quarters equals 26 two weeks equals 1 year Thus 2 quarters equals (2*26)/4 = 13 two weeks Example 3: How time period will be adjusted: Interest rate = 5% per half year Time period = 2 half months 24 half months equals 2 half years equals 1 year Thus 2 half months equals (2*2)/24 = 0.166667 half year The simple interest equation: FV = P + I I = P * R * T FV = P + P * R * T P * R * T = FV - P R = (FV - P) / (P * T) where: FV = Future value I = Interest amount P = Principal amount R = Interest rate (as a decimal, not in percentage) T = Time period