The
calculator is split into three sections:

Sliders
– Move the sliders to set the values of your principal, interest
rate, loan length, and mortgage start date.

Data
Display Options Area – Use the buttons to choose how you want the output to
be displayed:

Amortization
Graph – This shows how the total payment made each year is
broken down. Note how the curves show increased principal and
decreased interest being paid as time goes by. Also note that
extra payments "push" up the principal curve (i.e., the
annual principal amount shown is increased by the value of the
extra payment). See also the Settings Menu option for this graph.

Repayment
Chart – The percentage breakdown of the total payments made
over the entire mortgage (or indeed, the breakdown of the
average monthly payment).

Balance
Graph – This shows the balance outstanding over the term of
the mortgage. It is useful when extra payments are made to
visually see how much sooner the mortgage is paid off, and how
quickly the balance drops.

Annual
Amortization Table –
Shows how much interest and principal you will pay
each year.

Monthly
Amortization Table –
How much interest and principal you pay
each year, broken down month by month.

Settings:

Principal
Amount – One of the most frequently requested features
is the ability to
make the principal amount go higher. The ceiling for
the current version is set at 500 million units (e.g.,
dollars, pounds, etc.).

Static/Dynamic
– Static means that the calculations are done only when
you're finished dragging a slider; this is the default.
If
you have a particularly fast machine or Web Browser, you can
use dynamic mode where calculations are done as you move
the slider. Be warned that on some Browser/machine
combinations this can be too much for the Java virtual
machine implementation, and may cause the Browser to hang or
crash.

Interest
sliders – You can use either 1/8th increments or decimal
places.

Amortization
– The system used for calculating American monthly mortgage
payments is the same or very similar to many other countries
around the world. However, Canadian financial institutions use a
slightly different formula.

Dollars/Pounds/Euros/Rands
– This is purely cosmetic.
It makes no difference to the
calculations.

Amortization
Graph – Normal mode works as described in the
amortization graph section above. Stacked mode shows
principal, interest and extra payments all stacked on top of
each other. Unlike normal mode, there is no overlap between
data.

Monthly/Biweekly
Payments – Limited support for biweekly mortgages is
present through this option. When biweekly payments are
selected, an extra halfmonthly payment is made every six
months. This equates to making 13 monthly payments every 12
months—a close approximation of how a typical biweekly
mortgage will work out.

Input
Boxes

Initial
Loan Data – If you don't like using the sliders, you can
enter data directly in this section. Values for the Tax and
Insurance fields are simply divided by 12 and added to the
monthly payment amount. The inflation figure allows estimates in
real terms to be calculated (i.e., in "today's money").
The total interest paid over the entire mortgage is shown on the
right hand side along with the total interest paid as a
percentage of all payments made (see the Repayment Chart for a
graphical view). Finally, the total interest paid in real terms
is displayed—this figure is an attempt at calculating how much
the total interest paid is worth in real terms.

Prepayment
Data – This section gives you the opportunity to estimate
how you can shorten the term of your mortgage by making either a
single oneoff payment or continuous extra monthly or annual
payments. On the righthand side, the Savings field shows you
how much money you will save, while the Real Savings field once
again uses the inflation rate to give a rough estimate of what
these savings are in real terms given that the interest savings
are spread over a number of years. The dates shown reflect what
happens to the mortgage term when the extra payments have been
factored in.
Important:
When entering values into the "Input Box", make sure to press
"Return" after you enter the last value. Using the
"TAB" key
will work on some browsers, and clicking the mouse over to the next box
is fine too, just make sure the last value you enter has been recognized
by the calculator, and is being taken into account when calculations are
made.
If
you are unable to even enter data in the prepayment fields, there is a
good chance that the problem is with your Browser. Try upgrading to the
latest version, or try the applet on a different machine with a
different Browser. 