I’ve made the appropriate changes and APR is being calculated correctly.

Download link: WordPress Mortgage Calculator Plugin

Here’s the changelog:

== Changelog ==

= 1.3 =
* Fixed broken APR calculation. Closing costs were being added to the “amount borrowed”, which was used in APR calculations, so the APR ended up always being equal to the stated interest rate.

= 1.0 =
* Initial release

Get it here: http://www.mortgagecalculatorplugin.com/download-wordpress-mortgage-calculator-plugin/

Get it here: http://www.mortgagecalculatorplugin.com/download-wordpress-mortgage-calculator-plugin/

And feel free to tell me what you think in the comments!

Installation:

1. Upload `mortgage-calculator` directory to the `/wp-content/plugins` directory
2. Activate the plugin through the ‘Plugins’ menu in WordPress
3. Place the following code where you want the calculator to appear on your site.

<?php wp_mortgage_calculator(); ?>

4. This plugin is can also be activated as a widget in WordPress’ widgets screen.
5. I tried to wrap all elements in their own IDs or classes so that you can have full control over the styling of the calculator if you’re comfortable with CSS.

== Frequently Asked Questions ==

= Can this plugin be used as a widget? =
Yes. You can activate this plugin as a sidebar widget.

= Does this plugin have to be used as a widget? =
No. You can add the following anywhere in your theme you want the calculator to show up:

<?php wp_mortgage_calculator(); ?>

I’ve finally finished the updates and testing on my WordPress mortgage calculator plugin. You can see the final implementation in the sidebar of this website. I’ve tested it pretty thoroughly, although I need some beta testers who are willing to run the calculator on their website and keep me apprised of any errors so that I can flush out any remaining bugs in the software.

If you’re interested in being a beta tester, leave a comment on this post. The comment form asks for your email, which will not be displayed so you don’t have to worry about spam, but make sure you enter the best contact email so that I can get in touch with you and send you the files and help you get the plugin setup if need be.

APR Calculation Using the Actuary Method

One of the bits of this calculator plugin that I’m really proud of is its use of the Actuary method of calculating APR (also known as the iteration method). There are a number of ways to approximate the annual percentage rate using different algebraic formulas, but none of them are as accurate as the Actuary method, which is one of the only two methods for calculating APR approved by the Federal Trade Commission for use on Good Faith Estimates.

I’m not sure what other mortgage calculators online use, but my research suggests most of them use one of the approximation methods. So, using this calculator means you can provide your website visitors with the most accurate method of APR calculation available.

In my searches across the web looking for a solid mortgage calculator plugin for WordPress, I was disappointed at what I found available. So, I went ahead and wrote my own, which has since been used on a number of projects. In keeping with WordPress’ open source tradition, I’m publishing that plugin here for everyone’s use.

I’ll try to provide timely support in the forums, but I can’t provide support for general WordPress issues. I have to say that because in a forum like this, I inevitably get a million questions totally unrelated to the project from people looking for me to practically build their websites (or their clients’ sites) for them. Obviously, I don’t have time for that, and off-topic posts really dilute the quality of the forum, so they will be deleted without explanation. I don’t mean to be harsh on this issue, but I seriously get about 30 general web development questions a day and I simply don’t have time to provide an explanation when I don’t answer those questions. Please keep things on topic so that I’m better able to provide support for everyone.