On the theme page, you’ll find this:
Tested on: WordPress ver x.xx
Preview on: WordPress ver y.yy (Strict Test)
The theme score is based on the result that runs on the WordPress ver x.xx
ThemeGrade.com always run on the latest WordPress ver y.yy so when you click on the Preview link (normal or strict test), you’ll see how the theme works in the most current WordPress version.
WordPress releases new versions quite frequently so it will be hard for us to retest all the themes every time WordPress updates its program. However, we have devised a method to keep the themes as updated as possible:
We will retest the themes when the tested WordPress version is more than 5 versions older than the latest version. For example, if a theme is tested on ver 2.5 and WordPress releases 5 versions in 2 months and the latest version is 2.6.3, we’ll retest that theme on 2.6.3 onwards.
We will retest the themes when there is a major WordPress upgrade.
We will give first priority to retest a theme if it is a certified Gold, Silver or Bronze theme.