Mortgage Calculator (Help)
Calculator not loading? You probably need to
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
- Data display - use the buttons to choose how you want the
output to be displayed:
- Summary - just shows a summary of the current
- 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
- Repayment Chart - the percentage breakdown of the
total payments made over the entire mortgage (or
indeed, the breakdown of the average monthly
- 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 - how much interest and
principal you pay each year.
- Monthly Amortization Table - how much interest
and principal you pay each year, broken down
month by month.
- Principal Amount - one of the most
frequently requested features of the
older versions of the calculator was the
ability to make the principal amount go
higher. I've put a ceiling of 500 million
in the current version.
- 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 can 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.
Canadian financial institutions use a
slightly different formula.
- Dollars/Pounds - This is purely cosmetic.
It makes no difference to the
calculations. People in my part of the
world just prefer using the pound sign!
- 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
- Monthly/Bi-weekly payments - Limited
support for bi-weekly mortgages is
present through this option. When
Bi-weekly payments are selected, an extra
half-monthly payment is made every six
months. This equates to making 13 monthly
payments every 12 months - a close
approximation of how a typical bi-weekly
mortgage will work out.
- Input Box
- 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. On the right-hand side, the total
interest paid over the entire mortgage is shown
along with an estimate in real terms (i.e. in
"today's money") given the figure for
inflation entered in the subsequent section.
- Prepayment Data - this section gives you the
opportunity to estimate how you can shorten the
term of your mortgage by making either a single
one-off payment or continuous extra monthly
payments. On the right-hand 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
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 the next box is fine too, just make sure
the last value you enter has been recognised 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.