This plugin adds a date calculator to your site to help you determine a date into the future and the past. It accounts for leap years, and you can choose hours, days, weeks, months and years. You can adjust for only 8-hour business days when choosing per hour or business days when choosing by date. This is a useful date calculator for many purposes.
You can download the Web321 Date Calculator Planner plugin from the downloads area here
Here is the plugin in use.