Installation on a WordPress Sidebar
For this, you will also need a theme which allows Sidebars on Pages. Plus, if you only want the Calculator to appear on a specific Page(s) then you will need a theme which lets you have multiple custom sidebars and thus you can setup a specific sidebar for your desired Page(s).
To Install Using the Default WordPress Text Box Widget
- Go to Appearance, Widgets and drag an instance of the Text Widget onto the required sidebar.
- Create a Page for the Calculator, or edit an existing page.
- Change the Page Setup/Page Layout or however your theme describes that functionality so that a Right Sidebar or Left Sidebar shows. And if you can define a custom Sidebar for this page then do so too.
- Click on ‘Update’ to publish the new page.
Installation in the Main Content of a WordPress Page
There are some plugins which allow you to add a Widget within the Page (or Post) content area. In theory, therefore, you could add a Widget similar to the above and then use a separate Plugin to post it within a Page.