Comments on: How does this calculator work?
http://ask.metafilter.com/111854/How-does-this-calculator-work/
Comments on Ask MetaFilter post How does this calculator work?Fri, 16 Jan 2009 12:45:20 -0800Fri, 16 Jan 2009 12:45:20 -0800en-ushttp://blogs.law.harvard.edu/tech/rss60Question: How does this calculator work?
http://ask.metafilter.com/111854/How-does-this-calculator-work
How do mortgage calculations work? <br /><br /> As an always-have-been-and-always-will-be renter, I've been free to ignore mortgages and how they're calculated. But now, for work, I need to understand how they're calculated. Specifically, I need to understand how the mortgage calculator on this page works:<br>
<br>
https://www.uamc.com/locator/Calculators (select "What Will My Monthly Payments Be?" on the left panel)<br>
<br>
Can this be distilled down to a mathematical equation that a programmer on my team would understand? <br>
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This is in California, if it makes a difference.post:ask.metafilter.com,2009:site.111854Fri, 16 Jan 2009 12:28:02 -0800missmobtownmortgagesformulacalculationsmathsBy: OmieWise
http://ask.metafilter.com/111854/How-does-this-calculator-work#1608008
They work like any other loan works. They follow an amortization schedule based on the term of the loan, and the (property tax + insurance)/12 is added in each month. The Appraised Value in that calculator doesn't change anything, although it does change the amount that the mortgage can be written for.comment:ask.metafilter.com,2009:site.111854-1608008Fri, 16 Jan 2009 12:45:20 -0800OmieWiseBy: bensherman
http://ask.metafilter.com/111854/How-does-this-calculator-work#1608043
<a href="http://www.vertex42.com/ExcelArticles/amortization-calculation.html">This page</a> explains how to calculate an amortization table.comment:ask.metafilter.com,2009:site.111854-1608043Fri, 16 Jan 2009 13:06:07 -0800benshermanBy: thinman
http://ask.metafilter.com/111854/How-does-this-calculator-work#1608229
This is an ActionScript payment function I wrote a while back. It jives with other online calculators:<br>
<br>
<code><br>
public static function pmt(P:Number, r:Number, n:Number, t:Number):Number<br>
{<br>
// Loan Payments<br>
<br>
// P: Principal borrowed<br>
// r: APR expressed as a decimal<br>
// n: number of payments per year<br>
// t: total term of loan in years<br>
<br>
r /= n; // Interest rate applied per billing cycle<br>
return P * (r+r/(Math.pow(1+r, n*t)-1));<br>
}<br>
</code><br>
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For instance, if you calculated the payment on a $100,000 30 year loan at 5%, paid monthly, it would look like this:<br>
<br>
<code><br>
var monthlyPayment:Number = pmt(100000, .05, 12, 30);<br>
</code><br>
<br>
That would return 536.82. The calculator you reference rounds up to 537.<br>
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The tax and property insurance would just be added together, divided by 12, and added to the payment amount calculated by the function.<br>
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I don't know how they are calculating the mortgage insurance cost. It is likely just a percentage of the principal.comment:ask.metafilter.com,2009:site.111854-1608229Fri, 16 Jan 2009 15:46:40 -0800thinman