1RM (“one rep maximum”) is a Dashboard widget for Mac OS X 10.4 “Tiger” that calculates the maximum amount you can lift given a submaximum lift. So for example, if I can lift 75 pounds 10 times, then according to the widget below, I should be able to lift 100 pounds once (as seen in the 100% row). The other percentages are handy for determining what to lift for a given “effort level.”

Making a Dashboard widget is pretty easy. There are a few extra Javascript routines you can use (and the ability to use other code that I didn’t need), but otherwise it’s fairly straighforward application of HTML, CSS, and Javascript to make a mini “webpage.” The one thing that I had to learn was to make some icons and backgrounds. This was “image processing” at a different level than I am normally used to. I used a Mac port of the Gimp (an open source alternative to Photoshop) to make the icon, the front, and the back of the widget. I was impressed with the Gimp; now when is an Illustrator alternative going to emerge? Is Inkscape the best right now?

UPDATE: Here are the installation instructions Apple says I should tell you:

Mac OS X 10.4 Tiger 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.