Financial Interest Calculations

Financial Interest Calculators offer flexible methods for money and interest loans, mortgages and savings. The calculation is based on 5 main variables ( N, I, PV, PMT and FV. Given 4 of the variables the remaining can be calculated. Two additional variables make the calculator more flexible, the Period ( P) and After/Before ( B).

One example is this version of the Financial Calculator written in Java (Java Applet) and JavaScript.
Because of the problems lately with Java I decided to redesign the application. The current version works with PHP and AJAX (jQuery/JavaScript).
In case the calculator does not function as expected or you have other problems, please read the Help Section below.

Mechanism

A few agreements are used to enter the correct values to the variables.

Type operation	Agreement	Applies to	Example Desctiption for Input Calculator.
Payments	Are always negative. Do not use a valuta-sign.	PV, PMT, FV	To enter a payment of €100,= use -100.
Revenues	Are always positive. Do not use a valuta-sign.	PV, PMT, FV	To enter a revenue of €250,10 use 250.10.
Durations	Are always positive	N	To enter a duration of 10½ years use 10.5.
Interest	Are always positive and in percentages and year-based.	I	To enter 3.25% per year use 3.25.

Main Vars

Duration - N

The duration is measured in years. To make Period Payments possible during parts of the year use the Period - P settings to select the period. The duration can not be negative.
The column Duration contains in the 2nd row the input field for the duration value in years. The 3rd column contains the calculated duration in days.

Example 1	Example 2
In case of a mortgage with a duration of 30 years, input 30 (N = 30). The row below contains the calculated duration in days (i.e. Duration is 10 years meaning 10 x 365 = 3,650 days).	In case of a loan with a duration of 2½ years, input 2.25 (N = 2.25). The row below contains the calculated duration in days (i.e. Duration 2¼ years mening 2.25 x 365 = 821 days).

Interest - I

The Interest is always given as a percentage per Year. The column Interest contains in the 2nd row the input field for the interest value. The 3rd row contains the Interest calculated as rate per Period.
The interest can not be negative nor can it be greater than 75 %.

Example 1	Example 2
In case of a mortgage interest percentage of 1.79% per year, input 1.79 (I = 1.79). If a monthly period (See the Period column) has been chosen, the 3rd row will calculate a monthly interest of 0.1500%.	In case of a loan interest percentage of 1.79% per year, input 1.79 (I = 1.79). If a ½-year period (See the Period column, choose half-year) has been chosen, the 3rd row will calculate a monthly interest of 0.8910%.

Present Values - PV

The Present Value is the current or now value. Do not use valuta-sign and use a decimal point as separator. Comma fields-separators are not allowed.

Example 1	Example 2
In case of a mortgage of €250,000.00, input 250000 PV = 250000).	In case of a initial payment for a saving account of €50,000.00, input -50000 (PV = -50000)

Period Payment - PMT

The Period Payment is the amount of money which is received (positive value) or payed (negative value). The number of revenues/payments per year depends on the chosen value of Period - P.
The 3rd row in the Period Payment is the indication of the interest payment (revenue (+) or debt(-)) for the chosen Period.

Example 1

For a mortgage of € 250,000.00 a monthly periodical payments of € € 921.50 is required, input -921.50 (PMT= -921.50). Suppose for an annuity the chosen values are as shown in image 2 (P= Month, B=After, N=30, I= to be calculated, PV=-250000, PMT=921.50, FV=0) the calculated value for interest will be 2.00% per year (0.1700% per month) and the 1st Periodical Payment has an interest part of 416.67. Please note that the Interest Payment value of 416.67 is only valid for the 1st payment.

Future Value - FV

The Future Value is the amount of money which is received (positive value) or payed (negative value) at the end of the total duration.
Example: In case of a linear mortgage the end-value will zero (0).

Additional

Period - P

The Period chosen here is used for creating multiple Period Payments per year (PMT). Valid options are Half-year, Quearter, Month, Week and Day.
Example: In case of a mortgage normally the period is a month.

After/Before - B

The value before after in combination with the Period P is used to indicate payment before or after the chosen period. Example when chosen for the above setting and moving the After/Before switch to Before will result in an Interest Percentage of 3.2317% per Year in stead of 3.250%.
Example: In case of a mortgage the normal value is after.

Example Mortgage

Buying a house with a mortgage of € 250,000.- (PV = 250000), a End-Monthly (B= After, P = Month) Period Payment of €1,000.- (PMT = -1000) and a duration of 30 Year (N = 30) the Interest will be 2.6245% per year.
Same example but now with an Interest of 3% will yield to an Period Payment of €1,048.56 (-1048.56).


And when you put that amount of money on a bank with 3% Interest? Leave (After/Before B = A, Duration N = 30, Interest I = 3, Period Payment PMT = -1048.56). Change:

• PV = 0

And calculate the Future Value will yield € 606,815.34 (606815.34).
How much money did you actual pay? Change:

• I = 0

Resulting in € 37,8000.- (378000).

Help

The calculator is written in PHP and JavaScript using jQuery AJAX implementation. A previous version worked with Java and a JavaApplet.

Deprecated Java Version

The information below is not used anymore but contains information on Java Applets.
if the correct version of Java is installed this mechanism works fine on Windows and Linux. But unfortunately not on Apple Mac OS. The settings for JNLP Applets on OS X is totally ignored by default, so this feature has to be enabled by switching to run applets in their own process in the Java Preferences Panel . The Java Preference Panel is located in the Applications -> Utilities, choose the General tab

See also

• Financial Interest Calculator by Harm Frielink
• Pensioen, Intrawiki Pensioen van HaFr, not accessible for anybody else.