Adsense Split Testing Results for 250x250 vs 300x250

Last updated: Apr 30, 2008

If you remember back to the post I wrote, Using PHP to Determine Which Adsense Ad Works Best, we explored ways to split test the performance of Adsense with the help of PHP. I had also promised to share the results of my testing for the month of April. Below are my results.

I was surprised to find that on my particular blog the smaller Adsense ad was significantly more effective than the larger 300x250 ad. This is great news for you since there will be less ad space and more content.

Here are my results for the split testing of the two ad mediums.


48.27% of the clicks .59 CTR eCPM was 171% higher than 300x250 resulting in 73.03% of the revenue.


51.72% of the clicks .64 CTR eCPM resulted in 26.97% of the revenue.

Although the 300x250 ad had a slightly higher click through rate, the 250x250 ad out performed the other ad in terms of net revenues.

Have you split tested your ads? If so please share your results.

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