1RM version 1.1 1RM is a Mac OS X Dashboard widget that calculates your maximum possible lift (1RM, “one-rep max”) given the number of times a submaximal lift weight was lifted. For convenience, it also lists simple percentages of the 1RM calculated and a suggest number of reps for that weight.

The formula used to calculate the one-rep maximum is:

1RM = wt / (0.997568 - 0.0248505 * r)

where wt is the weight lifted r times.

Installation is straightforward. Here are Apple’s instructions:

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.

Version history

Version 1.3, March 2009 (download)
Enforced limits of 0-10 reps.
Version 1.2, January 2009 (download)
Tweaked formula to ensure 1RM is equal to weight when reps is 1; upgraded to fully Leopard-compatible (cosmetic differences).
Version 1.1, June 2006 (download)
Cleaned up interface.
Version 1.0, May 2006 (download)
Original version.

12 Responses to “1RM: Mac OS X Dashboard widget”

  1. michaelgalloy.com » 1RM 1.1: Dashboard widget update says:

    […] I updated the 1RM Dashboard widget for Mac OS X and gave it a permanent home. The only change to the widget itself is a bit cleaner interface (check out the 1RM page for a screenshot). […]

  2. dan says:

    Where is the formula from?

    thanks for listing what you used.

  3. Michael Galloy says:

    I fitted a formula to the table given in Periodization Training for Sports by Tudor O. Bompa. I also checked this versus a few other sources and seems very close to what everyone else is using.

  4. dan says:

    Bompa is excellent and without a doubt one of the best.

    Brzycki published one that is used commonly. It looks like this:

    Weight ÷ ( 1.0278 – ( 0.0278 × Number of repetitions ) ), so it’s a little different but maybe the predictions are very close as you said.

    Thanks again.

  5. eric says:

    Here’s my wish list…

    1) I’m curious if you could convert this widget into an iPhone app?

    2) Also it would be really cool if there was an option to create 1rm profiles so you could plug in your own math based on wt. and reps.

    I plan on getting an iPhone soon, and this would be ideal for taking to the gym..

    Thanks

  6. Michael Galloy says:

    I’m considering getting an iPhone if there is an update at WWDC. If I get one, I would probably be interested in getting 1RM on there.

    The different profiles is a cool idea.

    Neither idea will probably be implemented soon (i.e. earlier than August), though.

  7. michaelgalloy.com » 1RM 1.2 says:

    […] made a few changes to my 1RM Mac OS Dashboard widget. This computes a theoretical one-rep maximum given a weight and number of […]

  8. jim says:

    what unit should the weight be e.g kg or pounds ???

  9. Michael Galloy says:

    The units of the 1 rep max are in the same units that you enter the weight you lifted.

  10. Rob says:

    This is not accurate — I just put in that I could lift 75 LBS 30 times and my 1 rep max is 300. There is absolutely no way that is possible.

  11. Michael Galloy says:

    This is a bug in the input validation. Only reps 1-10 should be allowed.

  12. Michael Galloy says:

    OK, this is fixed. More than 10 reps (or less than 0 reps) will now give an error. See version 1.3 above.

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