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Split Testing: How To Increase Your Adsense Earnings 94% Overnight

Posted By Darren Rowse 16th of August 2008 Adsense, Blog Design 0 Comments

In this post Brian Armstrong from StartBreakingFree.com shares some tips on using Split Testing to increase his AdSense earnings.

Long time readers of ProBlogger know that Darren is a big fan of split testing ads to improve your earnings. I took this advice to heart, and wanted to show you some real world results that I got on my own blog.

Feel free to take these results and apply them to your own site. Or better yet, do some of our own testing and improve on them even more!

I split tested 3 separate regions of my site and looked mostly at eCPM to compare them. If you aren’t sure what eCPM is click here. I think it’s better to use eCPM than click through rate (CTR) because it incorporates not just how often it’s clicked, but also how much you make per click.

Right Aligned vs. Left Aligned Ad In Post Body


This ad region makes the most money for me, and was smack dab at the top of each individual post page (but not on the homepage).

  • The right aligned ad got a 0.78% CTR and $1.41 eCPM
  • The left aligned ad got a 1.30% CTR and $5.31 eCPM

Clear winner: left aligned (276% improvement)

It’s hard to say why this is exactly. Maybe the left aligned ad looks more like it’s actual content instead of an ad. Whatever the reason, the difference was substantial.

Top Right: image vs. text


This ad resides at the very top right of every page. I had been running it with image ads for a while and decided to test it against text ads (with some appropriate color choices).

  • The image ads got a 0.35% CTR and $1.74 eCPM
  • The text ads got a 0.33% CTR and $2.15 eCPM

Interesting to note here that although the CTR went down slightly, the eCPM went up. This seems to indicate that the text ads were paying more per click. So even though it was clicked slightly less often it still made more money overall.

Winner: text ads (narrowly)

Under Posts: image vs. text


This ad was placed at the bottom of each post page and also on the homepage under the excerpts. I again decided to test some text ads against the incumbent image ads.

  • The image ads got a 0.58% CTR and $1.86 eCPM
  • The text ads got a 0.43% CTR and $2.27 eCPM

Again here the CTR went down and the eCPM went up. Also worth noting is that the color scheme I used on the text ad block is consistent with my site. “Blockquote” tags on my site use a similar color scheme.

Winner: text ads

Conclusions & Next Steps

For those who are curious, here is the actual data from an excel spreadsheet. You can pull this out of Adsense under the “reports” tab if you use different channels to compare different ads.


Overall these results were impressive. The site-wide eCPM from these three ads went up overall from $5.01 to $9.73 which is a 94% improvement.

I could just convert all ads to the better performing version and call it a day, but what I’ll do instead is continue testing….forever.

There are plenty of other things to test, such as…

  • Trying text ads in the post body (since they performed better elsewhere)
  • Left aligning ads under the posts
  • Trying different color schemes
  • Trying other types of ads (Amazon, Performancing Ads, Text-Link-Ads, etc)

Most people focus on growing their blog’s readership to boost earnings. This is a critical component, but don’t forget about the other major tool in your arsenal: split testing.

What ad formats and placements have worked best for you? Leave us a comment below.

To get more tips like these, check out my blog at StartBreakingFree.com. It’s is a blog for people who’d like to quit their 9-to-5 jobs, start their own business, and achieve financial freedom. I’ll even give you 3 of the top 10 books on building wealth for FREE when you subscribe, instantly delivered to your inbox! Check it out.

About Darren Rowse
Darren Rowse is the founder and editor of ProBlogger Blog Tips and Digital Photography School. Learn more about him here and connect with him on Twitter, Facebook and LinkedIn.
  1. Nice case study, I guess maybe a bigger amount of impressions is needed and everyone’s situation will be different, but this is good for a WP blog I guess
    thanks :)

  2. thanks for the informations. I’ve never done such research. And this is really helpful. It makes me wonder that whether i’ve done well to my adsense placement

  3. Thank you for your thoughtful analysis. It would take me a couple of months to come up with the same results.

    Though I’m not monetizing my blog at the moment, I plan to in the near future. You have saved me a lot of time and trouble.

    Thank you again!

  4. awesome presentation of split testing… very thorough!

  5. I find the image vs non-image split testing a bit odd.

    I think it should also be compared to a combined block. Because supposedly, Google is supposed to optimize against this automatically.

    You may need a larger number of impressions to get an accurate comparison.

  6. A very thought-provoking post.

    That Right Aligned vs. Left Aligned Ad thing left me all confused though. Can anybody explain why we have such a huge difference there?

    Anyhow, I did my own testings long time ago and I’m happy with what I have at the moment. If somebody can give us a very good explanation about the Right Aligned vs. Left Aligned Ad thing, I will tweak my ads further.

  7. Really thorough. Like Mike said, it would have taken me a long time to figure that out. Thanks.

  8. This is great info. Once you have thousands of Ad impressions to play around with, this kind of testing is very useful to maximise earnings.

  9. Great post. I’ve done testing like this before but never with these results. Probably because my split tests were for ad color, not text / images ads. I think I might have to go try more split testing, thanks.

  10. this is an awesome post. I will really take all this information and use it for any adsense I might use on my blog. This has to be one of the best blog as I have read this week or even this month

  11. I agree to first finding, as the day i added my left aligned image add in the post my earnings increased by a big percentage.

    I regularly experiment, on my blog and till now i have success only with adsense not with chitika or adbrite networks.

    my two cents, use one ad network for all your ads, it works for accumulation, otherwise you may find that you earn money but it did not meet minimum criteria for it to get released from ad network

  12. thats a very good idea. i heard of split testing before..i used it for adwords once.


  13. What an motivational post! Time for a busy weekend setting things up :) The key is to get data so you can do the analysis.

  14. So you eventually decided to give up adsense in favor of a sponsors box in the sidebar? I went to check out your site, and I don’t see any adsense anywhere, so I’m assuming you found direct sponsorship or affiliate 125 x 125 paid better than the text ads?

  15. I’ve been scouring for an answer to the left / right adsense positioning all week!

    You’ve made my day with this one… good timing!

  16. Wow..! Great Post.
    Images helped to understand easily.
    Thanks Brian

  17. The reason the left aligned ads do well in posts is because people’s eyes are trained to read left to right. If they’re starting off, they’ll see the ad on the left before they see it on the right.

  18. The left aligned ads inside the post works a lot better because it has been scientifically proved that the majority of human beings start looking at a page from left to right, just like we read. That means that Ads placed on the left side of the page are the first things we see. That’s why web sites and blogs should have the sidebar on the left side. But it’s all about how you want your web site / blog to look.

  19. It is better to use text ads than image ads. Text ads earn better than image. It is easier to blend text ads into your site than image ads.This is one lesson.
    The other lesson, If you are using adword, it is cheaper to advertise with image ads than text ads.

  20. Thanks for sharing those numbers, Brian, they’re quite interesting. For one thing, I would think the image ad on the top bar would be much more effective because it looks a lot easier to read and stands out. I need to start playing with advertising options on my own blog.

  21. I too have found putting a large rectangle to the left of the text works better. I think this might be because you read left to right, so you’ll see the ad first.

    For whatever reason though, I want to say it’s against Google Adsense’s TOS to post actual statistics. Check out #7: https://www.google.com/adsense/localized-terms

    I could be misunderstanding this though.

    Good post.

  22. Thank you very much for this great guest post! This was definitely the most usefull blogpost this week for me. :) Thanks for revealing all the data.

    I now have all AdSense placements on the left side on my German tech blog. Let’s see what it brings. I hope I’ll see the results you have.

    Best Regards from Germany and of course I now have your blog in my feedreader.


  23. Really interesting post BUT I’d of of thought you’d be breaking Adsense TOS by sharing exact numbers like that. As far as I’m aware you can share overall revenue but that’s it.

  24. The question remains how you actually do the split testing? Do you have a javascript that randomly changes the placement/type for each visit? Or, do you run one type for a day and another type for another day – week? month? How do you guarantee that the compared time periods have no differences other than the type of ad?

  25. Awesome information. I am getting my content ads left aligned right now.

    Thank you Brian and thank you Darren for inviting him.


  26. I can see I need to do some rethinking and some testing of my own.

    I appreciate that you took the time to document this experiment and I know I’ll be using this to jump start my own research. I most liked that you actually included the numbers of clickthroughs compared to earnings.

    @axioblogger -> It might be cheaper to buy image ads, but with this information they’re likely to be fewer sites running them!

  27. Great post and one that inspired me to changing my right aligned ads to left aligned at 3 this morning, i am very eager to see if this makes a difference. I get quite a few thousand imps daily and consistant CTR so i should see the results good or bad soon!

  28. Great info! My blog is too new to have adds but I hope to be able to try these tests out when I get to that point. Thanks for the useful advice.

  29. Brian,

    An excellent blog post!

    A very, very useful (and interesting) test campaign, that shows several things.

    The human brain always think the ‘common’ practice as the norm – i.e. placing ads on the left side of the texts, is, to me, simply natural… more often than not, we see images aligned to the left of posts/articles.

    To add, understanding how human brain and ‘subconscious’ mind act on advertising is key to better conversion and click thrus.

    Thanks for the great post!

  30. Very interesting figures. Funny I always prefer right align myself but thats just down to personal task and believing its best to start with text so that it flows better down the left side (to do with the whole reading from left to right thing). Will certainly reconsider now.

    Yet another post to bookmark from problogger!! :D

  31. Thanks for the kind words everyone!

    @Nimic – no I still use Adsense, the 125×125 ads in the right side bar are performancing ads, I’ve only been using them for a week or so, but have yet to sell a single ad, so that test is still running

    @arn – you are right I think it is worth testing these against a text+image block where Google rotates them for you. I have seen mixed data on this, can anyone confirm whether Google will split test image vs text for you?

    @Brett – Interesting, yeah the wording isn’t quite clear. Hopefully they don’t mind.

    @Markus – thanks for the kind words Markus and welcome to my site :)

    @William Cox – as for how to actually do split testing technically, Darren shows one method in the link I put in the article. You can also use PHP code like this which is what I do. This alternates two ads evenly:

    Not that it wouldn’t really be a fair comparison to rotate ads by time (run one ad for a week, the next second week, etc) because during that time your visitors could be coming from different sources (lets say you hit the digg front page, and a different type of user floods the site with different interests, etc). This way (rotating ever visitor 50/50) is the most accurate I think.

    Best of luck to everyone!
    Brian Armstrong

  32. I have placed ads on the sidebar like most and channeled it with opposing STAND OUT COLORS or bland site wide colors and I do have to admit, a bland site color ad will do better than a bam in your face ad as I have proved.

    Thanks for the great post, I am going to go test somethings now.

    You can check out my ad placement if you would like, as of right now it is doing great!

  33. It filtered out my PHP code in the example above, but what you want is something like this:


  34. Wow, thanks for doing the homework for us! I’ve read how text ads seemed to perform better than image ads, but this proves to the contrary.

  35. Some great tips. I love how you actually broke it down comparing the CTR of the various options.

  36. Darren, I suspect the reason text ads seem to be doing marginally better (I say “seem to be” because I have just enough training in statistical analysis to be dangerous) is that before someone clicks through a text ad, they have to read and comprehend the text; thus, more “buy in” (or “commitment”?) before clicking.

    But with the graphical ad, even fairly subtle ones such as your example, the internal processing is probably more along the lines of “Hmm…what’s this? *click* Oh…an ad; nahhh…*back*”

  37. bill perry says: 08/16/2008 at 3:08 pm

    I think Al is on the right track. Isn’t it against TOS to disclose specific CTR and non-revenue information?

  38. The reason why Left ads work better than Right is because Americans read from left to right.

    Another example is my Theatre class. When our director wanted an actor to stand out in a scene, she would direct him/her to come downstage LEFT. She explained that this is most powerful spot on the stage, because Americans naturally read from left to right.

    Great post by the way!

  39. I know that our eye have some preference on a newspaper page layout [some study prove it already]. But you refine this concept, and apply in blog ads.
    Thanks for your sharing.

  40. it is interesting the note the difference of performance between the left aligned and right aligned adsense ads.

  41. You have inspired me to change the type of adds I have and placement of those adds on my site I have added a verticle Ad bar on the top right hand side I wanted to do a longer one down the left hand side but after numerous failed attemps to adjust the Blogger template I settled for my current version. Question how much is too much. I liken this to product placement in video games you want it to enhance the experience without detracting. anybody have some good examples of balance
    If you get a chance checkout http://kidzense.blogspot.com and let me what you think about the ad to content balance


  42. I feel the clear winner in our case is the 300×250 ad format, irrespective of anywhere we have put it

    Other major winner is the link ads, if placed appropriately, churn in a good amount of revenue


  43. good post. in general for most people, i think text ads are best. but i also believe it’s contextual. so if you have a site where people sit and read then text ads are better. many gaming sites with graphical elements say that image ads are better.

  44. Thanks for sharing such a nice piece of information.

    I’m a big believer in implementing the strategies of Google Adsense through split testing that are guaranteed to explode Adsense clicks & earnings.

  45. Thanks Darren, I get all your Posts in my Reader, but I Came to your Blog to Comment,
    A Great Innovation,
    We all Know these thing, but no one Bother to Test and Experiment it.
    The narration was too good.
    You deserve to earn so much money from your blogging.
    I really Appreciate it.

  46. Yes, this is really something I need to do more of.

    Once I started making a comfortable living from my websites, I got a little lazy about continuing to grow and experiment.
    And even in the beginning, I was a bit lazy about split testing.

    Since my first websites were all hard-coded with straight html (with each Adsense unit pasted in by hand, thank you very much), it was pretty laborious to go in and make a lot of changes. Since my newer sites are all based on WordPress or MT, and it’s a simple matter to make a change to the template, I should definitely try tinkering a bit. Thanks for the reminder!

  47. Thanks for sharing your case study,
    I will surly try this on my own blog,

    However, I have big ad block under my post headings. I need to research to get it aligned on left of the text.
    If any one knows about it, please suggest me, how can i do it in my WP blog.

    Thanks & Regards,
    Vikash Kumar

  48. This post is great. I have 35,000 to 40,000 impressions per day, yet I only have 2.0 eCPM and 5% CTR. I think this would help increase both my eCPM and CTR. :)

  49. Great article. I guessed wrong everytime – When I “knew” the answer before I continued reading! I guessed ads on the right and image ads over text ads. Thanks for the wake up!

  50. Very nice article, i have just started to monetize my blog. I have found that adverts in the navigation bar which appear on every page work well.

    I am not to sure whether to ad in text adverts, as this may make readers feel a little put off.

    However i believe i shall test this on some of my more popular articles.


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