Is it good to convert wp blog to php website? I want to place calculators on my site but not in plugin form. Please comment If I do so...will this effect the ranking or PR of my blog?
Your question makes no sense. A Wordpress-site IS a PHP-site - no need to convert anything. Just make the pages with whatever calculators you wanna add. (And please explain why in all that is holy you don't wanna use plugins). Granted - if you're talking about a wordpress.com based blog, I can understand it slightly, but still, why not just put up a proper installation of Wordpress on your own domain? And if you ARE talking about a proper WP-installation on your own domain, you need to sit down and understand a little bit more of what you wanna do.
A WordPress "Theme" is just a series of standard PHP scripts that are wrapped around wordpress. You can create an entire Web Site with custom php programming for WordPress and it as a CMS.
It looks to me like you've looked at the plugin process, got scared off and don't want to learn. If you convert your site to a series of php scripts without a CMS you'll learn the hard way why systems like WordPress and drupal are so popular.
Or took a look at the absolute garbage turdpress vomits up and has the cojónes to call markup, the halfwit "multiple entry point" "security, what's that?" endless files for nothing, and host of other glaringly bad indications of developer ineptitude, and is now trying to do the smart thing... Get the **** off Turdpress.