Compound interest calculator with graph help

Settings Remark
Time period (T) Time period (T) is the length of time that the money is borrowed or lend.
Decimal numbers can be entered.
The interest (I) is calculated at the end of each compounded period.

There are two ways to specify the time period:
• Method 1:
Enter a value and select the unit time period: days, weeks, bi-weeklies, semi-monthlies, months, bi-monthlies, quarters, semi-annuallies or years.

Using bi or semi in front of time periods means:
• bi = every two
For example:
bi-weekly = every two weeks
bi-monthly = every two months

• semi = twice a
For example:
semi-annually = twice a year
semi-monthly = twice a month

• Method 2:
Select a from date and to date.
The number of days between the from and to date is the time period.
The nominal interest rate (R) is specified per year. If the time period (T) is set to another unit than year for example weeks, the calculator will adjust the time period accordingly.

Example 1: How time period will be adjusted:
Interest rate = 5% per year
Time period = 7 weeks

52 weeks equals 1 year
Thus 7 weeks equals 7/52 = 0.1346 years

Example 2: How time period will be adjusted:
Interest rate = 5% per year
Time period = 2 quarters

4 quarters equals 1 year
Thus 2 quarters equals 2/4 = 0.5 year

Example 3: How time period will be adjusted:
Interest rate = 5% year
Time period = 5 bi-weeklies

26 bi-weeklies equals 1 year
Thus 5 bi-weeklies equals 5/26 = 0.1923 year

The compound interest equation:
 T = log(FV / P) or T = log((I / P) + 1) N * log(1 + (R / N)) N * log(1 + (R / N))

where:
FV = Future value
I = Interest amount
P = Principal initial amount
R = Nominal interest rate per year (as a decimal, not in percentage)
T = Time period in years
N = Number of compounding periods in one year