The Versatile Unit Converter is also available as a Mac OS X Dashboard Widget

Download VUC widget 1.13

VUC.zip
(100 K; August 20, 2019)

Mac OS X 10.4 Tiger or above is required. If you’re using Safari, click the download link. When the widget download is complete, show Dashboard, click the Plus sign to display the Widget Bar and click the widget’s icon in the Widget Bar to open it. If you’re using a browser other than Safari, click the download link. When the widget download is complete, unarchive it and place it in /Library/Widgets/ in your home folder. show Dashboard, click the Plus sign to display the Widget Bar and click the widget’s icon in the Widget Bar to open it.