I wore this on my waistband when I went to the gym as I know the gym machines are not very accurate. I normally use the elliptical and the recumbent bike. The book that comes with it does not explain what setting to use with the elliptical, so I tried the bike setting first. After about 10 minutes, it said I'd burned over 200 calories, so I changed it to the weight setting to see if that would be more accurate. Well, it wasn't either! Then I went to the recumbent bike, and of course used the bike setting. After 2 hours at the gym, the thing told me I'd burned 2000 calories! While I wish that could be true, there's no way it's possible. The gym machines tell me that I've burned 1000 calories after 2 hours, and even those machines tend to overestimate calories burned. The X-Max Caltrac Calorie Counter was even worse, and therefore useless. I sent mine back.