If someone in this forum tells you that it is accurate, then, presumably they measured it on their own monitor and it is then accurate on their monitor with their resolution settings. Such an answer would have nothing to do with your monitor or settings.
If you’re asking this question, then one would assume that you don’t have enough computer knowledge (it gets technical) to ensure that your computer has the correct settings and based on your question, as pointed out above, I wouldn’t accept another person’s answer which says that it is accurate, as conditions vary.
Furthermore, even with the correct settings, the best you can hope for is ‘nearly accurate’.