While we're all being conditioned by health-care pros to "know our numbers" – from cholesterol to blood pressure – precisely what constitutes normal for testosterone seems less clear. When the Endocrine Society first set their guidelines in 2006, they did so based on the readings of some 120 males (dropping the highest and lowest few percentiles) and arriving at a range between 288-1,000 (ng./dl.), with most doctors setting the cut-off point for men at 300. But even this number is merely a guideline, and it's not unlikely that normal men with no symptoms of low testosterone would have levels in the 200 range. Most doctors agree that the number should only matter if you have multiple symptoms of low T, and like Dr. Gregory Bernstein, believe a number may be highly individualized. "Some men may live at what would be considered a low level, and that's normal for them," he says. "Whereas other men need higher levels. It goes back to the question that we don't know what truly is normal."