Stumbleupon Algorithm Unearthed?

How does the Stumbleupon algorithm really work.? I have no idea, and I doubt anyone else really does know for sure, other than core programmers at Stumbleupon.
I do know one thing though, Tim is probably the person who has spent the most time studying Stumbleupon, analytically.

Whilst I really appreciate facts, where there are a lack of facts I appreciate discussions that at least try to create models based upon extensive research data

You might find this a little geeky, but for those that like delving into how things might work, Tim’s modelling of the Stumbleupon algorithm is just pure gold.

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  1. says

    An interesting analysis, of course it’s to question how close it is the truth it might be worth to go by and see what sort of effect it gives.

    • says

      It ties in with some of my experience, though I feel some users might have a very heavy thumb down potential to kill a story, and I have sent that information to Tim in the past.

      I made sure I didn’t present it as fact, but I don’t know anyone else who studies Stumbleupon in such a detailed manner.

  2. says

    I think it really needs to be stressed that this is my theoretical model I have no special knowledge other then literally hundreds of server and analytics logs. My volunteers who helped me were a mixture of my students, friends and bloggers with an interest in Stumbleupon. I did try to contact Stumbleupon to ask if I was on the right lines :) I didn’t expect a reply and so wasn’t shocked when I didn’t get one.

    But at my heart I’m an engineer it doesn’t matter if its a car or algorithm I love breaking it down and trying to put it back together.

    • says

      Tim, I wasn’t part of the test group yet can relate to all you point out.

      There are so many posts about SU that think they have something pinned down. Flyingrose has a lot of good experience, so has Doshdosh, but you are the only one I have seen who has really managed to capture the essence of Stumbleupon in an equation that makes sense.

  3. says

    Like Slevi said, I’d be interested to see how the thing works if implemented. Of course, wouldn’t stumble just change their algorithm if someone came close to unearthing it?

  4. says

    Tim, I have read your post and the comments. Seems that many readers are stumbling your post (including me). I hope you can use that for statistics for your further research. It could not be 100% accurate but it will be a nice figure to see.

  5. says


    Thanks for the info. I have been struggling with Stumbleupon for months and it looks like the only way to be successful is to have lots of friends and aquantances stumble your posts.

    • says

      Very true. I have been struggling for the past few months, and most of the times I have to ask my friends to stumble my links.

      Anyhow.. thanks for the info :)


  6. says

    Definitely a key factor is also category/tags when it comes to how Stumble-power translating into real hits on a page. However, that wasn’t within the scope of the AMAZING analysis to which you linked – probably the best attempt I’ve seen to rigorously analyze StumbleUpon. Three thumbs up!

  7. says

    Definitely a key factor is also category/tags when it comes to how Stumble-power translating into real hits on a page.

    Your right tags and categories are incredibly important but not regarding number of visitors but type of visitor. The tags and categories are used by stumbleupon to send targetted visitors those who expressed an interest in the category or tag, by explicitly telling stumbleupon (categories) or thumbing up (categories + tags). Certain tags and categories have a much larger following then others cooking vs webdevelopment for example and will attract stumblers with larger audiences meaning your chances of being stumbled by or thumbed by some one with a higher audience is more likely.

  8. says

    I figured out the algorithm!


    A = X

    A – The ACTUAL level of quality for the content

    x – The amount of visitors

    Unless people are thumbing up bad pages…..

  9. says

    Hi Andy. I found your post via EZ Money Online…sorry if it is too late for comments on this page.

    I was wondering something about Stumble recently. How important do you think pictures are for popularity? Maybe it is something really obvious but it seems like every page that comes up when I stumble has weird or amazing pictures on it.

    • says

      Interesting pictures can play a role in grabbing attention – you are unlikely to thumb a page up if it doesn’t attract your attention.

      That being said, I am not a fan of eye rest images that are included just to add interest. I know lots of people have success with relatively random pictures from Flickr, but it just doesn’t interest me.

      If you can add on topic pictures, that is a good option