Pitch Grid test is a relative pitch test which evaluates your ability discriminate pitch-distances.
The test notes are laid out as a grid. There are four rows of octaves that range from C2 through C5. The grid sensitivity determines the number of columns. E.g. 100c corresponds to 12 columns (chromatic scaling); 33c corresponds to 36 columns. This allows pitch-distances exceeding half-step precision to be assessed. The grid sensitivity is 1200 cents. This is because the grid only has one column. To pass the test, you must click in the correct row in which the played note was played. After you have answered 10 questions, the test will continue with a grid sensitivity level of 600 cents. The grid now has 2 columns. The grid sensitivity decreases as you answer more questions. In turn, the number of clickable columns increases. This increases the difficulty - you have to listen more carefully to find the destination note. This leads to longer answer times.
The Pitch Grid Test might seem like an absolute pitch test. It is actually a relative pitch test. The grid highlights the last played tone and serves as your reference tone for the next question. The Pitch Grid Test allows for you to choose the grid sensitivity to which you want to test grid sensitivities you already know. The test will stop if you don't answer all ten questions about a given grid sensitivity. The relative pitch score is calculated from the grid sensitivity you used to answer each question in the past and the time it took you to do so. The answering speed is critical to assess your relative pitch ability. The relative pitch indicator also includes the answering time.