Increasing font size of link

Who Accepts Amex
February 2015
click through rate
Control and variation


Control A
Variation B
Whoacceptsamex is a UK based affiliate website that lists companies that accept American Express in the UK. They wanted to increase the number of external/outbound link clicks and hired the agency Lone Goat to assist. After analyzing the website it was found that the conversion rate of the company page templates was low. So it was decided to improve the company template and particularly the size and font of the company link (A  click on this link is the conversion goal for an affiliate site like this).  


  Increasing the font-size of the company name leads to more outbound clicks on that link


6 variations from font-size 12px to 18px (with 1px increments) where tested. After 28 days, the variation with font-size 18px emerged as the winner and recorded 33% more clicks.

Font size Conversion improvement
14 px control
17 px -16%
18 px +33%

The astonishing part, though, was that the variation with font-size 17px (just 1px less than the winning variation) recorded 16% less clicks as compared to the control (14px font-size). All other variations performed somewhat better than the control.
Note that font styling — bold, underline, no styling – was also tested, but did not show significant improvement.


Font size matters for WhoAcceptsAmex. It is surprising though that a 17px font (-16%) vs 18px font size (+33%) make such a difference in results. It would be interesting to repeat the tests and see if the result are reproducible.

Test details

Test element Font
Page type Product
Test date February 2015

Website information

Company Who Accepts Amex
Market Advertising
Test result
Test element Font
Page Product
Result +33% click through rate
Tool VWO

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