Does anyone know how accurate the heart rate monitors are that tell you how many calories you burned? Can it also tell you how many calories you burn throughout the day? For example, if I wear one for 24 hours (all day and through my workout), will that be accurate? Will it show how much I burned for that day?

If these really work for even just exercise, which one is the best to buy?

Even a high end model ($150+) will only be 80% accurate. You can get a good idea of how many calories you burn by using this calculator:

http://www.freedieting.com/tools/calorie_calculator.htm

A heart rate monitor is a wonderful tool to help you train safely and not overexert yourself. You will get a good idea of just how hard you need to work to burn calories without over doing it. As far as it being an accurate way to track calories burned...I would suggest using a free website as listed above. It will be nearly as accurate.

I don't know if I'd be accurate for non sporting related activities, I think they have those Bodybugg things for that. I have a Garmin Forerunner 305 and I love it for running and cycling because the GPS and average speed functions keep me on track during training.

The heart rate monitor is completely not accurate for me though, if you wear a sports bra with it it shows abnormally high heart rate figures (like 186bpm when I can still talk normally). For cycling (with a normal bra), the figures are quite accurate. The calories burned tend to be accurate, and I have cross checked them against websites (like caloriesperhour.com) before. For my 1/2 marathon, it said I burned nearly 1,600 (for a little over 2hrs running), and other websites estimated 1,700-1,800. Close enough! So thumbs up for the forerunner from me!

oh wow! I guess I should just stick with the online calculators. Its just SO hard for me to wrap my head around a 90min hot yoga class burning almost 1000 calories!!! I would only have to do one class a week if that was the case (goal is to burn at least 1000 calories in exercise a week)

I'm not so sure about the 1000 calls for the yoga... hmm... I normally give myself 100/30min for hot yoga - 100 cals per mile for running and 50 per mile for biking. HTH

I don't know that I would believe the 1000 cals for 90 mins of hot yoga, either.

I wear a heart rate monitor, and it seems generally accurate most of the time. It does give a high heart rate sometimes, and sometimes a low one. They seem to balance out.

I know people who wear one 24/7, but it can't be all that comfortable with a chest strap. The Go Wear fit & BodyBugg have much more comfortable bands for long term wear I think.

I always worry about the margin of error with those monitors plus the cost alone deters me. I could never wear one 24/7 b/c my six year-old son would be pulling at it, lol.