Calculators
Calcamm
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The down payment = The price of the home multiplied by the percentage down divided by 100 (for 5% down becomes 5/100 or 0.05)
$ = $ X ( / 100)
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The interest rate = The annual interest percentage divided by 100
= % / 100
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The monthly factor = The result of the following formula:
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The monthly interest rate = The annual interest rate divided by 12 (for the 12 months in a year)
= / 12
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The month term of the loan in months = The number of years you've taken the loan out for times 12
Months = Years X 12
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The montly payment is figured out using the following formula:
Monthly Payment = * ( / (1 - ((1 + )-())))
The amortization breaks down how much of your monthly payment goes towards the bank's interest, and how much goes into paying off the principal of your loan.
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Amortization For Monthly Payment:
\$" . number_format($monthly_payment, "2", ".", "$thousands_sep") . " over " . $year_term . " years
\n");
print("
\n");
// This LEGEND will get reprinted every 12 months
$legend = "\t\n";
$legend .= "\t\t| Month | \n";
$legend .= "\t\tInterest Paid | \n";
$legend .= "\t\tPrincipal Paid | \n";
$legend .= "\t\tRemaing Balance | \n";
$legend .= "\t
\n";
echo $legend;
// Loop through and get the current month's payments for
// the length of the loan
while ($current_month <= $month_term) {
$interest_paid = $principal * $monthly_interest_rate;
$principal_paid = $monthly_payment - $interest_paid;
$remaining_balance = $principal - $principal_paid;
// Compute the data arrays for interest, principal and balance
$interest_array[$current_month] = array( "", $current_month, $interest_paid);
$principal_array[$current_month] = array( "", $current_month, $principal_paid);
$balance_array[$current_month] = array( "", $current_month, $remaining_balance);
$this_year_interest_paid = $this_year_interest_paid + $interest_paid;
$this_year_principal_paid = $this_year_principal_paid + $principal_paid;
print("\t\n");
print("\t\t| " . $current_month . " | \n");
print("\t\t\$" . number_format($interest_paid, "2", ".", "$thousands_sep") . " | \n");
print("\t\t\$" . number_format($principal_paid, "2", ".", "$thousands_sep") . " | \n");
print("\t\t\$" . number_format($remaining_balance, "2", ".", "$thousands_sep") . " | \n");
print("\t
\n");
($current_month % 12) ? $show_legend = FALSE : $show_legend = TRUE;
if ($show_legend) {
print("\t\n");
print("\t\t| Totals for year " . $current_year . " | \n");
print("\t
\n");
$total_spent_this_year = $this_year_interest_paid + $this_year_principal_paid;
print("\t\n");
print("\t\t| | \n");
print("\t\t\n");
print("\t\t\tYou will spend \$" . number_format($total_spent_this_year, "2", ".", "$thousands_sep") . " on your house in year " . $current_year . "
\n");
print("\t\t\t\$" . number_format($this_year_interest_paid, "2", ".", "$thousands_sep") . " will go towards INTEREST
\n");
print("\t\t\t\$" . number_format($this_year_principal_paid, "2", ".", "$thousands_sep") . " will go towards PRINCIPAL
\n");
print("\t\t | \n");
print("\t
\n");
print("\t\n");
print("\t\t
| \n");
print("\t
\n");
$current_year++;
$this_year_interest_paid = 0;
$this_year_principal_paid = 0;
if (($current_month + 6) < $month_term) {
echo $legend;
}
}
$principal = $remaining_balance;
$current_month++;
}
print("
\n");
}
//******************************* Graphics ******************************//
// This part Copyright (c) 2002 Chris Karakas
// http://www.karakas-online.de
//
// Compute the graph here
include ( "./phplot.php");
if (isset($balance_array["1"])){
$graph = new PHPlot;
$tmpdir = "./tmp";
$prefix = "chart";
$maxbytes = 10000000;
//Create a file with random name in the temp dir, starting with $prefix
$temp = tempnam($tmpdir,$prefix);
//Add the .png ending and rename it, otherwise some web servers will not serve it.
$temp_png = $temp . '.' . "png";
rename($temp,$temp_png);
//Specify this random file to be the output file of the image
$graph->SetOutputfile($temp_png);
$graph->SetFileFormat("png"); // is default anyway
//Don't draw the image yet
$graph->SetPrintImage(0);
//Don't output the file headers - we're inline!
$graph->SetIsInline("1");
$graph->SetDataType( "linear-linear");
//First dataset to plot
$graph->SetDataValues($balance_array);
//Specify plotting area details
$graph->SetImageArea(600,400);
$graph->SetPlotType( "lines");
$graph->SetTitleFontSize( "2");
$graph->SetTitle( "Remaining balance");
$graph->SetPlotAreaWorld(0,0,($current_year*12*1.1),($financing_price * 1.1));
$graph->SetPlotBgColor( "white");
$graph->SetPlotBorderType( "left");
$graph->SetBackgroundColor( "white");
//Define the X axis
$graph->SetXLabel( "Month");
$graph->SetHorizTickIncrement( "24");
$graph->SetXGridLabelType( "plain");
//Define the Y axis
$graph->SetVertTickIncrement(($sale_price / 10));
$graph->SetPrecisionY(0);
$graph->SetYGridLabelType( "data");
$graph->SetLightGridColor( "blue");
$graph->SetDataColors( array( "red"), array( "black") );
//Check size of tmp directory
$tmpdirsize = dirsize($tmpdir);
//If the size of the tmp dir has exceeded the maximum in bytes that we allow,
//delete every file in it! We check this only once per run.
if ($tmpdirsize > $maxbytes){
runlink($tmpdir);
}
//Draw the chart
$graph->DrawGraph();
//Now, the image is ready - print it to the file!
$graph->PrintImage();
//Set correct permissions
chmod($temp_png,0644);
//Determine the image size in order to set it correct in the img tag below.
$size = getimagesize ("$temp_png");
echo "Graphics
![](\"$temp_png\")
";
}
// Compute the second image here
if (isset($principal_array["1"])){
$graph = new PHPlot;
//Create a file with random name in the temp dir, starting with $prefix
$temp = tempnam($tmpdir,$prefix);
//Add the .png ending and rename it, otherwise some web servers will not serve it.
$temp_png = $temp . '.' . "png";
rename($temp,$temp_png);
//Specify this random file to be the output file of the image
$graph->SetOutputfile($temp_png);
$graph->SetFileFormat("png"); // is default anyway
//Don't draw the image yet
$graph->SetPrintImage(0);
//Don't output the file headers - we're inline!
$graph->SetIsInline("1");
$graph->SetDataType( "linear-linear");
//First dataset to plot
$graph->SetDataValues($principal_array);
//Specify plotting area details
$graph->SetImageArea(600,400);
$graph->SetPlotType( "lines");
$graph->SetTitleFontSize( "2");
$graph->SetTitle( "Interest vs. principal (monthly)");
$graph->SetPlotAreaWorld(0,0,($current_year*12*1.1),($monthly_payment * 1.1));
$graph->SetPlotBgColor( "white");
$graph->SetPlotBorderType( "left");
$graph->SetBackgroundColor( "white");
//Define the X axis
$graph->SetXLabel( "Month");
$graph->SetHorizTickIncrement( "24");
$graph->SetXGridLabelType( "plain");
//Define the Y axis
$graph->SetVertTickIncrement(($monthly_payment / 10));
$graph->SetPrecisionY(0);
$graph->SetYGridLabelType( "data");
$graph->SetLightGridColor( "blue");
$graph->SetDataColors( array("green"), array("black") );
//Draw the first chart
$graph->DrawGraph();
//Second chart on the image
//Second dataset to plot
$graph->SetDataValues($interest_array);
//$graph->SetDataColors( array( "blue"), array( "black") );
//We already got them in the first graph
$graph->SetDrawXDataLabels(0);
//Draw a legend
//Define the legend texts
$graph->SetLegend(array("Principal","Interest"));
//Set the colors for the legend texts
$graph->SetDataColors( array( "green","blue"), array( "black","black") );
//Draw the legend
$graph->DrawLegend(450,175,"");
//Set the correct color for the second chart
$graph->SetDataColors( array( "blue"), array( "black") );
//Draw the New data over the first chart
$graph->DrawLines();
//Now, the image is ready - print it to the file!
$graph->PrintImage();
//Set correct permissions
chmod($temp_png,0644);
//Determine the image size in order to set it correct in the img tag below.
$size = getimagesize ("$temp_png");
echo "
";
}
function dirsize($directory){
if (!is_dir($directory)) return -1;
$size = 0;
if ($DIR = opendir($directory)){
while (($dirfile = readdir($DIR)) !== false){
if (is_link($directory . '/' . $dirfile) || $dirfile == '.' || $dirfile == '..')
continue;
if (is_file($directory . '/' . $dirfile))
$size += filesize($directory . '/' . $dirfile);
else if (is_dir($directory . '/' . $dirfile)){
$dirSize = dirsize($directory . '/' . $dirfile);
if ($dirSize >= 0) $size += $dirSize;
else return -1;
}
}
closedir($DIR);
}
return $size;
}
function runlink($directory){
if (!is_dir($directory)) return -1;
if ($DIR = opendir($directory)){
while (($dirfile = readdir($DIR)) !== false){
if (is_link($directory . '/' . $dirfile) || $dirfile == '.' || $dirfile == '..')
continue;
if (is_file($directory . '/' . $dirfile))
unlink($directory . '/' . $dirfile);
else if (is_dir($directory . '/' . $dirfile)){
runlink($directory . '/' . $dirfile);
}
}
closedir($DIR);
}
}
//******************************* End of Graphics ******************************//
?>
This mortgage calculator can be used to figure out monthly payments of a home mortgage loan, based on the home's sale price, the term of the loan desired, buyer's down payment percentage, and the loan's interest rate. This calculator factors in PMI (Private Mortgage Insurance) for loans where less than 20% is put as a down payment. Also taken into consideration are the town property taxes, and their effect on the total monthly mortgage payment.
The calculations are visualized with the aid of two diagrams at the bottom of the page, the first one displaying the remaining balance, the second showing the interplay of monthly paid interest vs. monthly paid principal, both on a month/money coordinate system.
\n");
print("
